Crash and failure

From some days after a certain time I use my PC it starts to be very
strange, for example you can't load right a simple web page, compile with
Visual Studio 2005, open a Windows window, etc.. and crash (blue screen)
happens, too. What's the problem?

Maybe due to some recent updates? I removed some temp folders created by
Windows Update.. could it be the problem? How to roll-back to remove last
4-5 update?

Thanks,

Mhaxx