I tried, but while it hangs it won't load any utility to let me check, and the hanging is usually not long enough to do it.
In the end I got frustrated and reformatted to try again. All was working perfectly for a day or so until today, after installing a batch of around 50 KB series Windows 7 Updates, at which point it came back. I just did a system restore, and thus far (30 minutes in) all is going well... though it's a bit soon to know for sure.
Googling a few of the updates, kb977074 looks suspicious.
I have disable any automatic updates and will be installing updates 3-5 at a time until I can isolate which one(s) are causing this awful hanging problem