First page of this article describes how to register avast! Free Antivirus and configure its settings for optimum performance and security.
Automating and customizing avast! Free Antivirus scans
There are several predefined scans available in avast! Free Antivirus 8, but it is best to create and schedule your own ones - weekly and monthly scans. Leave the default scans alone and use these as on-demand checks.
To open avast! Free Antivirus, click its icon in Notification Area of Taskbar (aka System Tray).
To create your own custom scan, open Security tab, expand Antivirus tab and then click Scan Now tab. Click Create Custom Scan under the list of available scans.
Please note that you can select a default scan in avast! Antivirus Free 8 - this one will be launched after you click the big Scan button in avast! user interface.
Adding and scheduling a quick weekly scan
avast! Scan Settings window opens. Let's create a quick weekly scan first. Under Scan Parameters, type Scan Name. You can add your own Comment, but this is not mandatory.
By default, a custom scan is configured to scan all hard disks. Under Scan areas section, click the All harddisks item and select Memory from the list instead. Now click the next field - (select additional areas) - below and select Rootkits (quick scan) from the list. This adds one row to Scan Areas section and creates the next (select additional areas) item under it. Finally, select Auto-start programs (all users) from this newly added third row.
If you accidentally add more rows, click Delete button on the right to delete the selected row.
Open Actions tab from the left. Select the Try to remove only the packed file; if it fails, remove the whole containing archive option from the Processing of infected archives section.
avast! Antivirus will notify you only if infected items have been found during the scan. You can then move these to Virus Chest (default action). 
Open Scheduling tab from the left. Tick the Schedule this scan box and select Weekly from Schedule Type. Finally, set a start time for the scan in Launch time and Launch day fields. Please note that time has to be in 24-hour format, not AM/PM format - so 11 PM is really 23.
Click OK to schedule the scan.
The custom scan appears on the bottom of the list of available scans. If you want to, you can turn on the Default scan option for it - this will launch the customized scan after you click the big Scan button in avast! user interface (Home tab).
Creating and scheduling a monthly full scan
Back in Scan now tab, click Create Custom Scan button again. We will create a monthly full scan now.
Type Scan Name and select All harddisks and Rootkits (full scan) under Scan Areas. Under File Types, click Scan all files.
Open Sensitivity tab and enable the Scan for potentially unwanted programs (PUPs) option.
Move to Packers tab and tick All packers.
Click Actions tab and select the Try to remove only the packed file; if it fails, remove the containing archive option under Processing of infected archives.
Again, avast! will notify you only if infected items have been found. You can then move these to Virus Chest - this is the default action.
Move to Scheduling tab and enable the Schedule this scan box. Select Monthly from Schedule Type box. Set the start time in 24-hour format in Launch time fields and enter the day of the scan should be performed on in Launch day field.
Finally, click OK to add the scan to custom scans.
Checking scan logs in avast! Free Antivirus 8
If you want to see logs for virus scans already performed, open Maintenance tab and click Scan Logs tab.
Find a log that has "virus found" in Results column (the others are not interesting, right?), click on it once and then click the View results button.
This will open the log in avast! Scan Results window where you can see detected items, actions and results. Click Close.
Do not worry about log files consuming too much disk space - avast! Free Antivirus deletes logs older than 30 days automatically. Or if you are worried, select the logs you do not need and click Delete log button.
Managing avast! Free Antivirus 8 Virus Chest
As avast! typically moves infected files to a special folder called Virus Chest, this folder might start using some disk space in the longer run. Its default size limit is set to 256 megabytes in avast! Settings.
You might want to open Virus Chest once a few months and remove older items from there to free up disk space. You can also restore items from Virus Chest to their original locations in rare occasions when avast! sounds false alarm.
Open Maintenance tab and then open Virus Chest tab. You will now see all items in Virus Chest.
Select the files you want to remove from Virus Chest by holding down CTRL key on your keyboard and clicking each item with mouse. After you've done selecting, release CTRL key.
If you want to select all items, click the first one in the list, hold down SHIFT key and then click the last item. Release SHIFT key.
To delete the selected items, right-click one of them and select Delete.
avast! will confirm the deletion. Click Yes.
Using avast! Free Antivirus 8 silent/gaming mode
Silent/gaming mode is mainly meant for gamers, frequent movie viewers and people giving a presentation. If you are playing a game that is not full-screen, an avast! Free Antivirus pop-up message would interrupt the game. This might steal focus from the game window or even crash the game. You do not want that, do you?
Just to remind you - avast! Silent/gaming mode does not mute Windows sounds, it just disables its own popups.
By default, silent mode is activated for every full-screen application, but to be really sure that nothing disturbs you during gaming, presentations or watching a movie, right-click the avast! Free Antivirus icon in Taskbar Notification area and click Silent/gaming mode. If there is a check mark before the item, the mode is already activated.
Always remember to turn the silent/gaming mode off after you finish your games, presentations, etc! 
avast! Desktop Gadget in Windows Vista and 7
For Windows Vista and 7 users, avast! Free Antivirus 8 adds a Desktop Gadget with status report and buttons for opening avast! main window, updating databases and following avast! at Twitter, Facebook and blog. Windows XP and 8 have no support for Desktop Gadgets.
The gadget is especially useful for Windows 7 users, because avast! icon in Taskbar Notification Area (aka System Tray) tends to be hidden and users might not notice if avast! status changes from secured to something else.
In Windows Vista, the Gadget is always fixed to one size, Windows 7 users can rotate it vertically and horizontally.

The button on the left opens avast! user interface, or main window with current status. The second button from the left allows manual updating of avast! engine and virus definitions. Do not get this wrong - avast! Free Antivirus updates both its engine and virus definitions automatically every four hours, this button is just for those who like to check for updates more frequently or need to make sure the virus definitions are up-to-date before performing a manual scan.
As with any Desktop Gadget in Windows Vista and 7, you can easily hide or show avast! gadget.
avast! Free Antivirus messages
If virus definitions are out-of-date, a yellow exclamation mark is displayed on avast! Free Antivirus icon in Taskbar Notification area (aka System Tray). You should then right-click the icon, expand Update and click Engine and virus definitions.
On some slower machines avast! services start slowly and a yellow exclamation mark is displayed on avast! Free Antivirus Notification area icon. This might mean that one of the avast!'s services (aka Real-Time Shields) is not running. The status then reads "avast! Antivirus: Attention, your system is not fully protected". Also, the avast! Desktop Gadget in Windows Vista or Windows 7 will change its status to yellow exclamation mark.
Wait for a minute or two and the status will usually change to "Your system is secured" automatically.
If the status will not change back to normal after a few minutes, either click the avast! icon and then click the large yellow Resolve All button in avast! main window, or click the exclamation mark in Desktop Gadget. This will force all avast! Antivirus services/shields to start.

If avast! Free Antivirus 8 is completely turned off or it is unable to remove a threat automatically, a red X mark will be displayed in the lower left corner of Notification area icon and system status reads "avast! Antivirus: WARNING, your system is UNSECURED". The Desktop Gadget in Windows Vista and 7 will also change its status to red X mark.
This could also happen when your free license for avast! has expired. In that case, re-register for another free year.
Either click the icon immediately to open avast! Free Antivirus window and see what's causing the problem, or click the red X mark in Desktop Gadget.

In avast! main window, click the huge red Resolve All button. This should help at most times. As you can see from the picture, avast! Real-time shields have been turned off and that was the cause of the problem.
If clicking the Resolve All button does not help or you are unable to use it at all, I recommend reading the Install Malwarebytes Anti-Malware and Malwarebytes Anti-Malware on-demand scan articles.
Please start your computer in Safe Mode for malware removal!
If some malicious program tries to turn off avast! Free Antivirus, a warning window will appear with text "An attempt has been made to turn off a key avast! module ". Always click No here unless you tried to disable avast! Real-Time Shields yourself. Then perform an on-demand virus scan immediately.
To prevent malware from disabling avast! shields, activate the password-protection of avast! settings.
avast! Free Antivirus 8 has four different popup message types - blue ones are informational, green ones mean successful updates, yellow ones are warnings and red ones are alerts.
Here are two examples of alerts - Malware Blocked and Malicious URL Blocked. In both of these cases, no further action is required from your part.

In some cases, avast! Free Antivirus needs to schedule a boot-time scan and restart your computer to get rid of some nasty malware.
Always click Yes here! Although such boot-time scan might take up to several hours, it is absolutely necessary to delete viruses and malware.
And do not forget to use antimalware programs after the scanning and cleaning is complete! Read the Free anti-malware programs section for instructions.
During boot-time scanning you will be asked for an action if some virus or malware has been detected. Press 4 on your keyboard to move all detected items to Virus Chest.
The in-depth article about boot-time scanning and possible errors is here.




