I log in via an xdm prompt and log out by using c-a-bksp to kill X and get back to the xdm prompt. Occasionally, when I log out, the entire machine hangs (need to reset to reboot) with a blank screen. I think this happens when X is changing graphics modes. I have also seen this when booting the machine into the xdm prompt (it never makes it to the xdm prompt but instead dies just as it changes from text mode to graphics mode. I'm using a Matrox Millenium II PCI on a Dell 266 PII and Iiyama MF8617E monitor. I would be happy to give any other info you need. I intend to get a copy of RH5.2 -- maybe it won't happen there.
Please upgrade to the latest XFree86 RPMs at update.redhat.com. These are 3.3.3-x, where x >= 1. Add additional detail to this bug if the problem still occurs.
You may reopen the bug if it still occurs otherwise it has been closed to lack of responce.
A very interesting thing happened.... I couldn't find the bug with the search engine, so I entered a random number for a bug ID and here it is. I am experiencing a very similar problem, only not with xdm, and when switching between consoles using alt-F7. I am using RH5.2, a number nine revolution 3d card (with the imagine 128 driver), and a custom monitor (I was conservative with the refresh rates, etc.) The results are exactly the same. This happened as soon as I got X running on a clean workstation install.