fuzyy screen on high resolution in gutsy

i just finished upgrading all my computers to gutsy
they all work fine, HP laptop, 2 Mac Minis, 2 Desktops except for my work computer

I have a wide screen ViewSonic VX2035wm that supports up to 1680x1050 resolution
it used to be working just fine on feisty, but after the upgrade it all looks blurry now ...

lower resolutions look fine, it's only this one that's broken, i suspect it has something to do with the refresh rate (obviously! no?)

I did my homework, searched for similar bugs or forum posts, however all talk about high resolution resulting in a flickering screen, which is NOT what i'm getting, i can see everything on my screen, but it's all blurry ...

i messed around with all the possible screen settings with no hope, then i played around with xorg.conf with no hope either ...

here's what i tried:
- setting custom HorzSync, VertRefresh values based on the manufacturer's specs
- using a custom Modline
- using a custom Modline with different refresh rates
- using ati's binary driver

none worked ... any ideas ?

here's the forum post related to this with a copy of my xorg.conf file: http://ubuntuforums.org/showthread.php?t=589939