unknown LVM metadata header errors

[Phillip Susi <psusi@cfl.rr.com>]

When running update-grub, I get several lines of:

error: unknown LVM metadata header.

This appears to be caused by grub-probe locating the LVM PV label sector
on the underlying physical disk ( hd3,msdos1 ), and incorrectly
following the pointer to the mda header.  At this point, it has already
scanned the 4 physical disks, found the first partition on them, found
the mdadm 1.0 superblock, and correctly located the LVM PV label sector
inside (md/0).  The first few sectors of (md/0) ( 4 disk raid-5 array ) 
are aliased to (hd3,msdos1), but obviously the offsets are wrong since 
they are relative to the md array, not the disk partition.

My first thought was that once the mdadm superblock is found on the 
partition, that should take ownership of it and prevent scanning for 
LVM, but theoretically it is possible to have mdadm inside LVM instead 
of the other way around, and that would no longer work if you didn't 
scan for both.

Any ideas on what could be done to get rid of this error?