LCD monitor / gfx card / resolution / refresh rate problem

Hi there, I've never used these forums before, But in the past when i have had problems I've found some pretty accurate answers from Google on here so i though it would be an idea to check my problem by you guys.

Anyway, the problem is...
When i have my monitor set to 75hz refresh rate, i get a bit of screen flicker and its a tad annoying. When i change it down to 60 it rids it of the screen flicker but for some reason its expanding the desktop so a good 4 inches are being cut off. Im not sure whats going on as everything else is the same minus the refresh rate which i put to 60hz.

System:

Windows XP home 2002 version service pack 2
AMD Athlon 64 processor 3800+ 2.4ghz
1gb ram.
NVIDIA Geforce 7600 GT.


i have tried changing the resolution about with both 75 and 60 refresh rates but the one res i need for my monitor so it all looks tidy is the one that is being problematic. I also tried changing the refresh rate in the Nvidia control panel, same for the res. I cant work out what the problem is so i was hoping some one could maybe help me out.

The only thing i can put it down to is that it was a windows online update. Before it was working fine for me, i got the pc built for me about a month ago... i had it set to 1440 by 900, at 75hz.. noticed the flicker, changed it to 60 and didn't have a problem, switched my box on tonight and noticed the flicker, went and changed it to 60 and it went all Pete tong.

Please help :s

 

anyone??