P992 Focus Problems

Hello,

I have a Dell P992 19" Trinitron CRT on my Dimension 4300.  The system is three years old and the monitor is just over two years old.   I use the system roughly 70% of the time for text and 30% for graphics usage.  I have a NVIDIA GeForce2 MX 400 video card that is original to the system (certainly not the greatest card, but good enough for my purposes).  While doing text work, I use 1024 x 768 resolution with a refresh rate of 85 Htz.  While doing much of my Photoshop work, I switch to 1280 x 1024 at 75 Htz.  According to the documentation supplied with the monitor, both of these combinations are supported and are also the recommended settings.

Here's my problem: At 1024 x 768, at any refresh rate supported (I've tried 60-85 Htz), the corners of my screen are fuzzy and colors are slightly off in those regions.  That said, the screen remains sharp in the center.  But the problems really start when I switch to 1280 x 1024.  At that resolution, my entire screen is blurry and text is virtually unreadable.  This occurs regardless of refresh rate settings (60 or 75 Htz), as well.  I find I get a headache just looking at it. 

While this is occurring, my monitor does not make any unusual popping or clicking sounds, although it has had a high-pitched hum whenever the screen is mostly black ever since day one.  The monitor is ventilated properly and I don't have any flourescent, wireless, or microwave devices nearby that could be causing distortion.  My speakers are shielded, and as a troubleshooting step I tried disconnecting them but the problems described above still persisted.  Degaussing the monitor through the OSD controls showed no appreciable difference either.  I even tried another monitor on my desk.  A 4-year-old KDS 17" CRT works just fine at it's maximum settings (1024 x 768 at 85 Htz), with accurate colors and sharp text.  I've not tried moving my monitor onto say a neighbor's system sheerly because it weighs upwards of 65 lbs. 

With all that said, does anybody have any suggestions as to what the problem might be or how to go about fixing it.  It's hard to believe my $400 monitor is shot after only 2 years of use, but I've seen stranger things happen before.  For the record, the monitor is still under warranty, but the rest of the computer is not. 

Thanks for any help you can provide and sorry for the long-winded post.

Sincerely,

Jason