Resolution Problems

I am unsure what has caused my problem, so I was hoping someone may be able
to shed some light on it for me.
I am running, Vista Business 32bit, Intel Duo 6750, Gigabyte P35-DS3P MB,
XFX 8800GT 512mb (Factory OC), 2GB Kingston HyperX DDR2, Viewsonic VX2235wm
Monitor. (That should be enough info)
Everything had been working fine, but without any changes to hardware,
software or drivers I now have resolution problems.
Firstly, when I boot my pc up it all goes well until just after the “Windows
Vista” logo at the bottom of the screen comes up (during boot) the monitor
goes into standby mode. Now the only way I have found to get my monitor out
of this is to unplug the DVI cable from the back of my tower and plug in back
in. The monitor then runs as normal – SO THATS ONE PROBLEM.
Secondly, when the above problem first happened (and this is still
happening) my resolution is stuffed. My monitor can go up to 1680x1050 and my
Video Card can easily handle this. (Which it had been doing). But now I can
only achieve 1024 x 768.

So I really would like to know if anyone can put there finger on what the
problem may be. Oh yeah, I have uninstalled, updated, reinstalled drivers.
Currenly using the 169.25 Nvidia Driver.

Thank you in advance.

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E6750, P35-DS3P, XFX8800GT512 OC, 2GB Kingston HyperX, Viewsonic 2235wm,
CoolerMaster Mystique 632, CoolerMaster 600W, Zalman Cooling.