Yeah... Using unsupported monitors is a crap shoot. Sometimes they work with the config files, and some will just never work right.
I did a quick search over on the official forums and came up with this thread about a dell monitor:
http://support.discreet.com/webboard/wbpx.dll/read?278739,176
Basically, even though it has the right resolution, it doesnt have the proper sync rate, or something or other. Someone suggested using xvidtune to modify the horizontal sync pulse on your monitor to try and fix it.
Personally, I would just go buy the right monitor, and not mess around with something that may not work even with the right settings.
Is there a reason why you are using this Dell monitor? Did it ever work properly with your system? Do you happen to have access to an "approved" monitor?
moody glasgow
smoke artist / editor