[CentOS] Problems with latest 5.3 yum update and grub

I recently updated two 64-bit CentOS 5.3 systems via yum update.

- One system had two physical SATA hard drives - drive 0 was Windows
XP w/SP3 w/NTFS, drive 1 was CentOS;

- The other system had two physical SATA hard drives, configured via a
hardware mirror of RAID 1 (mirroring)


After the latest yum update, grub on both systems failed me, dropping
to the grub prompt.

For the dual-boot system, I ended up reformatting and reinstalling
Windows on drive 0.   The CentOS was not touched.   That system is
fine now.

For the RAID CentOS-only system, I experimented with removing one
drive from the mirror and CentOS booted as though it was reboot after
a fresh install, though there were some traces that something else
(like an upgrade) was mixed in, but didn't work right.   I ended up
deleting the hardware RAID and removed a drive.  That system works
fine now.

Has anyone else experienced grub problems with more than one drive
installed from a recent yum update?

I will not perform an update on any other multi-drive systems,
including servers, until I know things are fixed.

Thanks for any insights.

Scott