[pc prob]

OK, now where to begin w/my slew of problems which i'm not sure if they're linked or not. just recently my computer has been restarting itself and when it logs back on it says that it just recovered from a serious error/crash that couldn't fix itself. from what i'm seeing is that there is no rhyme or reason as to why it happens... it's all intermittent and not occurring on any particular program from what i can see. I have done several diagnostic checks ranging from anti-virus/spyware, a registry fixer, a computer optimizer, harddrive life checker, and the disk error checking tool in the properties of the C:... I am now a little boy lost in the woods.
Prior to this problem I reinstalled my OS (XP) and all of my software so i can avoid this type of situation or what have you (new install, fresh look, new lease on 'life') but i was wrong. I have a radeon video card that requires .net framework 2.0, thru the insallation i get an error message that goes as follow:
error 25015.Failed to install assembly 'C:\windows\microsof.net\framework\v2.050727\microsoft.visualbasic.compatab ility.dll' because of system error: 0x80131107
I just now realize that I have no service packs installed on my machine due to the fresh install, would that be the cause of the problem of the rebooting or the framework 2.0 or both??. If so would i need to install service pack 1-3 or can i just install sp3?? any help would be appreciated because i really want to play World of Warcraft w/out any hinderance lol and important computer work to boot.