Yeah, it's probably not the monitor.
You might try and add a better ground cable from the monitor to the wall. You may be building some fields up on the chasis that's getting back to the card in the ground. Try making sure you are well grounded all the way through the isolation transformer.
Oddball reason: If it is the monitor, it could be the video signals are too strong, too much input voltage from that card. One of the 3 IC's on that board may not like that.