Sidebar, Explorer and Desktop Windows Manager crash on startup

[edito]

Bought a refurb and it hasn't booted right from the first day. Formatted and reinstalled Vista Home Premium and updated it completely (twice) . Updated all drivers but no joy. Sidebar, Explorer and Desktop Windows Manager crashes on startup. Explorer crashes upon opening My Computer. Even IE8 crashes upon opening.

P4 631 3.0 G
1 G PC4200
Intel 945 integrated video
Any help would be greatly appreciated. Doing this for a friend.

 

[GhislainG]

It most likely is a hardware issue. Start by testing memory with memtest86+, make sure sure that the CPU doesn't overheat, if you have a crappy PSU, try a better one, etc. You may want to read this thread: http://www.tomshardware.com/forum/261145-31-read-posting-boot-problems