After installing FC4 over my old FC3 installation I got a kernel panic on the first boot. I haven't been able to start my system yet nor figured out anything on what can be wrong.

This is what I get...

This is what the installation defaults me to also, so it should have been set up correctly.

I have to drives, hda and hdb.
hda1 is the /boot
hda2 is a VML VolGroup00 with LogVol00 = swap, LogVol01 = /, LogVol02 = /home

It seems like it founds the system allright since it states its reiserfs and that's correct.
I've tried this twice now and have no other options to try exept going back to FC3 again...

Any ideas?

I would suspect that lvm modules are not built into your initrd and being loaded before the kernel attempts a pivotroot,
however I'm not sure how to prove OR fix it .

I would try an LVM2-enabled livecd like DFS http://people.debian.org/~jgoerzen/dfs/
and see if you can perform filesystem checks, etc.

I solved this problem a pretty odd way.

- I reinstalled the system with FC3 again, a clean install.
- After that I ran FC4 installation as an update of FC3 and told it not to do anything with the boot manager. No new installation of it nor a second one, just ignore the current one.

After the update I was able to boot normally, everything looks like it was after the FC4 clean installation.
I'm baffaled, but I'm happy that it worked and If anyone else has this problem I hope this helps

I've had exactly the same problem but instead of installing FC3 and upgrade it to FC4 I just erased the whole Linux partitions, created manually a swap partition and a ext3 partition
While installing FC4 I chose to remove all Linux partitions and make new partitions automatically and that worked
I don't know why but that helped me !