Framemaker 8 Undo

[mulholland4]

Hi,
 I have recently moved  from XP to Vista. When I save my frame files I
always get a message stating "Cannot be undone. Undo history will be lost.
OK to continue?" Apart from being annoying, especially when I save all files
in a book at once. Is there any way of turning this off? I never got this
message when I was using XP, is it a Vista feature?
 Thanks
Mulholland