I had the Vista reboot for a day. I tried Safe Mode and got hung at crcdisk.sys. I noticed a couple of interesting things, and now I have my computer back--I thought it was dead forever.
1). If you shut your computer down when you see the "Configuring Updates" screen, when you boot up again you will see the useless options to boot in safe mode.
2). If you shut your computer down shortly after you start it up, you should get different options: to either Launch Repair, or to Start Windows Normally. Choose Launch Repair.
3). I didn't watch the Launch Repair process the first time, and it didn't work. But by the third time I tried it, about 30 seconds in it asked me if I wanted to do a System Restore. Yes!!
4). When my computer restarted, the blue screen stated that it was back to Stage 1: Installing updates. It immediately skipped back to Configuring updates, and got stuck in the loop.
5). I got back into Launch Repair and did the same System Restore, but this time I didn't wait for the blue screen to load up. I shut the computer down shortly after starting it up, and if I recall correctly, it was at that point that I was offered a whack of new options. I chose system restore (there was also the option to go to a command prompt--finally!), and the two restore points I was offered were a day before the loop fiasco.
6). Ah, mon dieu. Everything booted up, I have my life back! The Word files I was working on look good. It just seems to be a matter of major patience and not giving up--your computer is not wrecked. Hang in there!