Click options, click display, click performance, then click 'advanced' at the top right of the window and you will get more options, including the max fps one. I had my max fps set to 40 for a long time (before new graphics card' just because it gave a smoother play experience - really EQ2 isn't an FPS, it doesn't need really high frame rates to still look OK. No idea why throttling the FPS would fix that issue though, sounds like a mouse/resolution issue to me. Try it anyway.
What resolution are you running your desktop at, and are you using desktop scaling (right click desktop - display properties)? Are you running eq2 in full screen mode or windowed (i.e. can you see your windows taskbar below the eq2 screen or not)