I had the same problem. Updated yesterday 7/8/2012. After re booting my computer it was so slow it was
un-useable. This morning it took about two hours to get to add/remove programs. I was able to delete it
and computer works fine. Had the same problem with AVG though not as bad as Avast.
Installed the lastest update on Friday; laptop is now freezing after reboot. Booted from avast rescue disc, did a full scan, found a couple infected files to remove - but still no improvement. Desktop will come up, and windows explorer will open but run very slow for a couple minutes, then freeze altogether. Can't open internet connection at all, so I can't run any online diagnostics - anyone else having problems after the last update?