http://www.msfn.org/index.html/_/security/avg-fix-for-computers-running-on-windows-7-64-bit-pl-r89
We are sorry to report that we have identified a potential conflict between one of our recent updates (3292) and a significant number of systems running on the Windows 7 64-bit platform that has caused systems to go into an infinite crash loop.
It appears that the problems are most prevalent in Windows 7 64-bit systems.
Users who have downloaded the update, prompted for a restart, but did not apply the restart yet are advised to manually delete the avgrs[x|a].exe and avgchsv[x|a].exe file from the system.