I also have win 7 64 bit os and am unable to get avast AIS working on my system. I did receive a memory error one time but my consistent issue is that all shields are off and I get an RPC error measage on the ui. I have tried many times to uninstall and submitted a ticket and the tech responded by telling me to do exactly what I told him I already did.. it proves that he didn't read the ticket I submitted where I explained the steps I took. Maybe these steps will help you. They didn't help me.
Hello,
>
> Thank you for contacting our support center with your concerns.
>
> Could you try to restart your pc several times? If it does not help, reinstall avast! completely, please. It seems to be the easiest solution of the problem. First from the Control panel via Add or remove programs and if it does not help try using the uninstall utility:
>
> 1. Use our uninstall utility - download it from
http://www.avast.com/uninstall-utility > (this is more reliable than uninstalling through Add/Remove Programs) and save it to your desktop. Run the utility from the safe mode (restart your pc and begin repeatedly pressing the F8 key).
>
> 2. Clean your cookies and Internet temporary files. More information can be found here:
>
>
http://antivirus.about.com/od/securitytips/ht/iecache.htm>
> 3. Delete manually all avast files, that can be found in avast! folders (concerning folders C:\Program Files\AVAST Software and C:\Program Files\Alwil Software and also C:\ProgramData\Alwil Software and C:\ProgramData\AVAST Software).
>
> 4. Restart the computer.
> Now download the latest avast! version
> It can be downloaded from here:
>
>
http://files.avast.com/iavs9x/avast_free_antivirus_setup.exe>
http://files.avast.com/iavs9x/avast_pro_antivirus_setup.exe>
http://files.avast.com/iavs9x/avast_internet_security_setup.exe>
http://files.avast.com/iavs9x/avast_premier_antivirus_setup.exe>
> Save the installation file onto your hard drive.
>
> 5. Install avast!.
>
> If you have Windows 7 or Vista, either install avast! with UAC disabled (
http://windows.microsoft.com/en-US/windows-vista/Turn-User-Account-Control-on-or-off) or run the setup file as an administrator (right-click on the avast! setup file and from the Drop Down Menu select the "Run As Administrator" option).
