VSS error 12293 after system disk clone (Win2003)

After cloning a windows 2003 installation from a single drive onto two mirrored drives using Acronis Disk Director, VSS no longer works, filing events 12293 and 7001 when trying to use backup tools, and additionally giving error 0x8004230f when accessing the Shadow copy tab of disk properties.

I've google-researched this quite throughly, and found a suggested fix[1]: replacing the MBR signature of the disk. This would cause windows to invalidate old shadow copy information, which supposedly would make it all work again. However, I am a bit nervous over this... Is there a possiblity of messing this up somehow, because of the mbr originating from a single disk install, and now residing on a raid mirror? Has anyone here had this problem and solved it? This method or another?

[1] http://kb.backupassist.com/articles.php?aid=2971 (under header Resolution 2)

newsid on a 64bit windows 2003 also destroys vss config. can be fixed -> http://support.microsoft.com/kb/940184/en-us