After upgrading my kernel to the latest rawhide (2.6.9) last night, rebooting caused the system to lock at the "Configuring kernel parameters..." message that appears as the third or fourth line from the beginning of the boot process. The system was not hard locked (I could press enter and the cursor went to the next line), but it sat their indefinitely. Going into single user mode and then immediately exiting allowed a normal boot. I eventually figured out that my X server was failing to launch, because I had my video driver set to "nv" (nvidia's proprietary 3d drivers) but had not yet recompiled the driver to work with the new kernel This stage of the boot process is when it tries to launch into graphical mode. Therefore, using single user mode (which does not use graphical boot) or turning off graphical boot explicitly. I believe that the boot process should recover from failing to launch the X server by falling back to standard text mode boot. Some users would not think to try single-user mode and would presume that their system was unbootable and required an OS wipe.
This appears to be a failing of the nVidia drivers... they really shouldn't *hang*, they should just fail to initialize. Assigning to rhgb in case it's hanging on X failure to start.
*** This bug has been marked as a duplicate of 135574 ***
Changed to 'CLOSED' state since 'RESOLVED' has been deprecated.