Try booting in normal mode and let the machine run for several minutes. Check out the hard drive activity LED on the case (if you have it hooked up) to see if you are getting any disk activity. Just because you don't see anything onb the screen does not mean that the disk/processor are not swapping info and struggling through at a crawl. It probably is completely locking from your description, but I would give it a few minutes to verify.
My system, running 98se, freezes if I have my printer plugged into my USB port. This would probably occur with ANY USB device, but other than a Microsoft Optical Intellimouse that apparently went bad, I only have the printer. One of my 2 USB ports is missing the black plastic piece that stabilizes the cable in the port, so I'm guessing I trashed my USB port while moving my system one day, which also fried my mouse. If I plug the printer into the good port after booting, I can use the port fine. It's a hassle, but I can live with it until I get around to upgrading my system again. Try unplugging any USB devices and see if that fixes the problem. It might, but my problem is probably rare.