Aghh I hate this error as it is a catch all for any problem at all.
Warning This fix is only relevant for this system and no other, using on another computer may cause problems
Be advised that when the fix commences it will shut down all running processes and you may lose the desktop and icons, they will return on reboot
Run OTL
[*]Under the Custom Scans/Fixes box at the bottom, paste in the following
https://dl.dropbox.com/u/73555776/OTL_Fix.GIF
:Commands
[CREATERESTOREPOINT]
:OTL
@Alternate Data Stream - 1146 bytes -> C:\ProgramData\Microsoft:PAy1UaWaUZMd2Kqup3EjtEfp
@Alternate Data Stream - 1018 bytes -> C:\ProgramData\Microsoft:SpwWlUUFbmKajImBmmV
:Commands
[resethosts]
[emptytemp]
[Reboot]
[*]Then click the Run Fix button at the top
[*]Let the program run unhindered, reboot the PC when it is done
[*]Open OTL again and click the Quick Scan button. Post the log it produces in your next reply.
THEN
Could you open an elevated command prompt
Go Start > All Programs > Accessories
Right click Command Prompt and select run as administrator
In the black box that opens type :
sfc /scannow
After it has completed reboot and then try Avast again