EoSD does something similar to me on my old Win98SE machine. (all this is without vsync because I didn't know about it back then) When the computer is first booted, if I play it quite soon after that, it plays at about an even 60 fps. Some time later (an hour?) it sticks to 58.88 fps, and more time after that (another hour?) it sticks at 62.50 fps and will never budge from that number until I reboot, thus repeating the cycle. I have no idea why it does that, and it was the only game that did that. It's also very reliable, because I don't have an instance of it not doing that. I would test it with vsync, but I managed to break the sound driver and can't repair it right now, and IIRC the games don't like no sound and won't run, though I could be wrong about that because it has been a long time since I really used that system.