I must have really shot myself in the foot on this one.
I reinstalled CentOS 4.4 (have to, for now) on my test machine, exactly the way it was before (same options anyway), but when it comes up, I get:
Booting 'CentOS-4 x86_64 (2.6.9-42.ELsmp)'
root(hd1,0) Filesystem type is ext2fs, partition type 0x83 kernel /vmlinuz-2.6.9-42.ELsmp ro root=LABEL=/ rhgb quiet
Error 15: File not found
Press any key to continue...
If I press any key, I get a garbled screen that is nearly impossible to read. So, I rebooted from the DVD in rescue mode, ran fdisk to verify that the partitions are set up correctly, ran e2fsck on all three formatted partitions (sde1 - /boot, sde3 - /, sde6 - /home), ran e2label to make sure the labels are set correctly and everything checks out. All the file images are present in /boot where they should be, and the device map shows hd1 is /dev/sde3.
Is my disk rotten or something? Everything is in the right place (so far) but it won't boot.
The test machine is of a type I don't recognize, it's running a 2.88GHz Xeon processor with 8Gb of memory, a 4-disk RAID SATA controller (currently configured as 4 separate drives, one of which is "spared" because it did go bad) and a WD hard drive as /dev/sde. It has a 17" FP monitor with an ATI <something> XL video card, though I doubt that last part is terribly relevant.
Suggestions welcome.