avg

at first you can use AVG Diagnostics tool to find a problem.
To provide the results of the AVG Diagnostics tool:
1. Download this tool to your Desktop: http://www.avg.com/filedir/util/support/runner_en.exe
2. Double-click the saved file, the tool will start automatically.
3. Type your e-mail address and a detailed issue description into the appropriate areas.
4. Click "Diagnose and send results.”

second I like to say my experience at this point:
The best way to overcome this situation, which I've been until now , is to run disk clean up and remove temporary files and than restart your computer. this solution usually work better then others mentioned as follow:

1. Resident Shield (click the Anti-Virus component in AVG and clear the "Enable Resident Shield" checkbox -> Save changes).
2. Online Shield (click the LinkScanner component and clear the "Enable Online Shield" checkbox -> Save changes).
3. LinkScanner Surf-Shield (click the LinkScanner component and clear the "Enable Surf-Shield" checkbox -> Save changes).
4. Firewall (click the Firewall component and click "Firewall is disabled" -> Save changes).
5. Identity Protection (click the Identity Protection component and clear the "Activate Identity Protection" check box -> Save changes).
6. Cache Server (click the Tools -> Advanced settings -> Anti-Virus -> Cache Server and clear the "Caching enabled" checkbox -> OK).