2 weeks ago I went to a friends house and formatted harddrive and reinstalled win98se and all his programs.
I also installed a new GF2 Pro 64 graphicscard.

It has worked perfect since then until yesterday.
All of a sudden the monitors resolution had changed back to 800x600 from 1024x768. When I try to change it back I get a message saying something like:

"Cant change monitorsettings. Check hardware for monitor in devicemanager."

I have done this and it looks like it always has. It says device is working.
I have reinstalled drivers for monitor, I have reinstalled drivers for graphicscard, I have downloaded latest drivers from nvidia.com and I have also reinstalled windows. Nothing works, still get the same error.

Can someone please help me with this one?

His computer is an old AMD 700 Mhz, motherboard is GigaByte GA-71XE, GF2 Pro 64, 256 Mb ram, 20gb IBM hd