Wonky Word Editing on MDD w/ OWC 9600 video...

[Buzz]

MDD w/ OWC mod'ed Radeon 9600 trying to cross edit a pair of Word docs, w/ one doc on each screen; one screen LCD, other CRT. Doc on CRT screen previously edited w/ Track Changes tumed on, doc on LCD plain vanilla. For some reason, which I'm hoping someone here will supply the answer to, the Track Changes doc doesn't scroll properly on the CRT; either the bottom goes blank, or redraws multiple copies of the last couple of lines as the doc scrolls up (vice-versa from top if scrolling down), yet behaves fine on the LCD. The plain vanilla doc works fine on either monitor, so I'm having a tough time identifying the source of the quirk; is it,
A) the MDD procs?
B) the 9600 video card?
C) the Sony CRT monitor?
D) the Word program?
E) something else?
F) a combo of two, or more of the above?

thanks,
Buzz