Hard disk no longer available in XP after installing Vista

Hello all,

I just installed Vista on my machine on a new partition, so that I now have
a dual boot configuration for XP/Vista. This basically works.

Now I have 3 physical hard disks, each with more partitions. The first one,
which is a "basic" disk on which the XP and Vista partitions are, works well
on bot OSes. However, the other two, which are "dynamic" disks, don't seem to
work in XP any longer since I installed Vista.

When I open "Computer Management" > "Disk Management" on XP, it shows both
disks in the list, but as being "offline" (and no partition data). There is a
context menu command called "Reactivate Disk" that is supposed to be used in
such cases, but it doesn't work (just displays a message that the action has
failed). Under Vista, the disks work without problems.

I think I can rule out a device-specific problem as it is the same with two
seperate disks. It might be a problem specific to dynamic disks. Is it
possible that Vista has modified the data structure of the disk so that it is
not accessible from XP anymore? Or maybe any other ideas?

Thanks in advance!

Michael