Whaaats Up!

I am running RedHat 7.3 and Gnome. On an old 'puter. I have the resolution to the highest settings my moniter can handle "14inch". I installed nessus 2.0.1, but when i run it, the screen comes up but it is 3 quaters cut off at the bottom i cant see the buttons near the bottom, even if i minmize it and nothing works and cant see the bottoms buttons of the GUI .I took off the borders on the NESSUS GUI, but nothing works --- soo i cant use nessus? I tryed this OPTION --- that was using my WINDOWS machine and SSH to the REDHAT machine and run nessus like that, but i get this error:

Gtk-WARNING **: cannot open display:


So i went to: http://www2.arnes.si/~sopjsimo/gimp/
and installed this on my windows machine:

gtk+-1.3.0-20030115-setup.zip

But still no LUCK is there something else i can try? To get this to work?

<EDIT: This is the only program i have had problems like this on this machine>
_Thanks Guys_