Resolution problem after installing nvidia geforce 8400GS

Hi everyone

Im having graphics problems with my computer, and I wonder if anyone can help.  I have a Dell C521 running XP, which used to have an ATI 128MB graphics card.  I recently replaced this with a 256MB nVidia Geforce 8400GS (following your instructions) but now I cannot seem to move my res on windows beyond minimum (480X640 or whatever it is)....though the colour is stuck on maximum. - I dont seem to be able to change the settings at all - even to make them worse neither on the graphics card's menu, nor the display settings page.

Now here are the funny(ier) bits.  Whenever I remove all drivers and restart the computer, the resolution is great, but the refresh rate is very low.  Then I install the nvidia driver (without restarting) and everything looks great, refresh rate is as I want it - fine.  Then when I restart after installing the driver the resolution becomes stuck very low, the screen comes up with a message (nonpreset mode) and it gets stuck like that.  It seems to be able to run Empire Total War (which requires most of the max capabilities of my new card), but not windows.

 

Just a check list to describe what I did, I physically installed the new card and installed the driver from the disc first up, had the res problems, updated driver from website, still problems, searched for new drivers for my motherboard and monitor - none. removed all video (the ATI and the nvidia) drivers, updated bios and windows, used driver sweeper to remove all traces of nvidia and ATI restarted, reinstalled new nvidia driver from web and got the same problem...  Ive checked with the vendors of my graphics card and theyre out of ideas, they suggest I exchange the card, which Im about to do, but since it can work fine as it does in some of the rare circumstances I described, it makes me think its some other issue.

 

Any advice would be much appreciated

 

Cheers

Dave