Same problem here, I can't finish level 5-5x becouse I have a CRT monitor and game run in 75 fps. So I switched game to window and forced Vsync in drivers, but game still runs in 75fps mode. BTW, I can't change desktop frequence to 60Hz, my nVidia drivers don't allow me to set that value lower than 75Hz.
So, what now?

Yeah, I need 60fps limit too. I have a big problem in level 5-5x, the first bridge dissapearing faster than meat boy is able to run, so I allways fall down. :(

I can't finish this boss level. In end of this level Dr. Fetus only stays on right and do nothing. So, I pushed two buttons and when I was in small button room saws moved thru my meat boy and don't kill him. And now I can't go anywhere. I tryed complete this level several times, but it's allwas same, stucked in that room. So I try to run out of that room before door block me inside again. But outside I can't do nothing and saws kills me.

http://cloud.steampowered.com/ugc/576668016271353572/D75DF016761C18DF8719AE46F2ACC4E0B8E6B84F/
http://cloud.steampowered.com/ugc/576668016271343567/508B6DE1F7CFE0E66C604DEEC2C09D94BA9B012A/

I tryed force Vsync in nVidia drivers, run game in low resolution window mode + with low details, but nothing help me.

My dxdiag: http://rapidshare.com/files/456985641/DxDiag.txt