rex84, have you tried to use the "GROM" with your monitor? I'm looking at the "splash" page for it online, and they mention being able to adjust your refresh rate, but there is no mention of how to do that. While 144 Hz probably is beautiful with the newer games, SH4 might be looking for a 60Hz divisible?? Or is that only selectable by the resolution used?
Do you happen to have an old LCD monitor you could try temporarily with either a VGA or DVI connection, and run at that monitor's 'native' resolution? See if you still have the same thing? Have you tried an HDMI connection instead of DVI? Any time you make changes on the computer though, be sure you match them in the game before "going in". Exit and re-start so that the new settings "take"...
