A single link DVI-D cable will work. You only need to use a dual link DVI cable for high screen resolutions and refresh rates. And if your video card and monitor are both set up for dual link but you use a single link cable, it will still work. You're just limited to single link screen resolutions and frequencies. If you really want to chase down the problem then this page
has a list of things to try. I'd just run in analog mode. It's hard to tell the difference between analog and digital with most monitors. On top of that, almost all FX5200 cards use the internal DVI transmitter which is not a good one. They often have problems at higher DVI resolutions and refresh rates anyway. Side-by-side comparisons between analog and digital usually look the same anyway.