I just installed FC4 yesterday - it worked fine until I updated the system (blech, no apt) and got the new kernel (2.6.11-1.1286). The next reboot the volume group was read-only and the system promptly crashed on login! Subsiquent reboots required a manual fsck (which crashed on first run) to get the disk into a workable state.
I booted into 1226 and it worked fine again, so I gave 1286 another try - same result. 1286 is gone.
I've got a thinkpad t40 (intel 1.5ghz x86). anybody else had that problem?