The version of X you are using does not yet know about DDR versions of the GF4. It can't probe the monitor for its ranges using whatever it's called. (ddc?) I know this b/c I also have a ti4200 and it's a major pain in my ass.
Anyway, you'll probably need to configure X 'manually' once you know the monitor's ranges from its printed manual or online documentation.
(I have had success with LCD's by stipulating a sync 'range' that consists of the maxvalue#-maxvalue#)
Don't do any of that above without 1st getting more advice from ppl who've dealt with this problem more recently and/or with recent versions of GF4 cards.
This post should be considered totally worthless as a guide to proceding ; I am just posting what I hope is a little light on the origin of the problem.