I have a Vista x64 PC that hangs intermittantly at shutdown (on the blue shutdown screen). Sometimes it shuts down normally; sometimes it sits on the shutdown screen forever.
Unfortunately I don't know when this started, so I can't isolate what software/driver is likely to be the culprit based on installation date. I'd rather not wipe this machine if I can avoid it.
Any tips as to how to go about diagnosing this issue?
Update - I'm not asking for someone to diagnose this for me - rather I'm asking for a set of general techniques and tools that I can use in future scenarios - I want to know how to diagnose the problem, as opposed to how to fix the problem.