Yeah, i'm afraid you'll have to reformat after you've thought of doing all I can think of
One thing though, try taking out all USB devices, etc on startup. Sometimes network cards interfere somehow with Windows randomly.
So try doing that.
Its possible though that its just corrupted itself
As for System Restore hiddjaio. This wouldn't be possible without being able to get into safemode.
SET UP A PARTITION:
I hope you've backed up recently... or like me which is great, have Windows on a different partition to what your datas on. You have less chance of losing everything
So for example, make a partition with about 5 gig on it for windows and some essential things, and then make another partition with the rest for programs/data. Also making sure you back up this frequently too just incase of hardware failure.
You'll find it alot less annoying when things go wrong then, and it also means after about 6 months you can re-install windows to speed things up when they start to slow down without worrying.