Hello Abokasee,

do you perhaps have a new monitor or graphics card?
I found out lately that the resolution of the desktop and the in-game resolutions need to match. Also, in ATI drivers there's a function to "force refreshment rate".
I've had the same problem like you and it turned out that setting a constant refreshment rate and selecting the correct resolution helped.
What kind of Graphics card and Monitor do you have and how are they set?

R'as