Problem: Moving slave IDE drive to another computer led to 'Dynamic Disk Unreadable' in Disk Management on WINXP. Returning to original computer now had same error.
To Fix: DiskPatch will rebuild partition structure and turn it into a basic disk with no data loss.
Make sure if disk >137GB you use WINXP (with SP2), otherwise chkdsk will delete orphan entries and data loss will result.