i have a VERY long thread going actually about my computer locking up all the time. I took my comp to Geek Squad and it seems that when I got it back my computer runs a little better even though they didn't do anything but a diagnostics BUT it also seemed to have a lot more viruses and spyware with it... I am not sure what they did but my computer never had problems with pop ups and explorer.exe errors and other errors I have been getting lately. It also still locks up but not as often as before. It actually locked up when i went to safe mode to run the AVG scan for you
EDIT: Heres that thread i was talking about...
my internet and youtube