Well I think I might of solved one problem and found another yay lol.
Reset the machine to some sort of end user state but explorer still crashed. Rang the PC firm and finally got hold of a guy who would actually try things out.
Ran a memory test and the screen went blank, so he told me it failed the test and to retry it with 1 stick in each time (tonights job).but I find it odd my PC can still see 4gb on startup, and even in the system info stuff.
He then asked if the USB drive was an old HDD in an enclosure so ofc I replied yes.
Uplugged it and reset the PC and the computer tab now works perfectly. Plug the drive in and it goes pear shaped. Apparently he found the same thing happening on another machine and SP1 appears to fix it. So he said to try and force an install of SP1.
Tried to get SP1, but the MS site throws up something about using the updater only to install stuff, but no option to get SP1 in there
Any direct links for it, or is it a bad idea ?
The PC works like a dream for the most part, cracking framerates in WoW, Crysis and C+C3 so far
Thanks very much for the help and links guys, really appreciate it.