i had this problem not long ago, i
think it was caused by WLM as when i switched to MSN it was fine and when i was offline but as soon as i signed in it re-booted my PC (or within 5 minutes max),
anyway - i did a system format and re-installed WLM with share folders off and got my mate to delete the files out of it and then i didnt get the problem and *touch wood* havent had probles since ( and i use both the share folders and WLM)
so i think it was just a corrupt file somewhere,
maybe a system format is to drastic for you? - but it's my security ( "it dont work
- il format it
") yer - sad i know, but it has worked with most problems including graphics card problems and reboot problems (this one) and a few others.
anyway, if it isnt to much hassle for you and nothing else works just try a format.