Control panel unable to change display

Hello,
My two PC’s control panels cannot any more change the display parameters of my video card ( TNT2 64 ).
All I changed was taking them to a vacation home we have, and connect them through an RJ45 “crossed” cable ( they’re usually connected via a hub ), and connect one of them to a local monitor.
I reinstalled the display driver of one of them, which restored the factory settings, but not the ability to change them.
My GHOST images are a little bit ancient.
Can someone help ?
Thanks,Jean-Jacques Vergier, Orleans, France.