Floating display !!!

[ZOCON]

Hello I am a linux newbie ! I am running RedHat 5.2 (Kernel 2.2) on a Cyrix MII  computer with  64MB RAM, 2.1 GB HDD, S3 Trio64V+  Display Card, CTX  6468 Color Monitor and have a 128  MB swap space. In linux when starting XFree86 I am getting a floating type display in which  some part of the window is out side the screen and every time I have to move mouse up and down to see the top and bottom part of the window. Does anyone have any idea what could have caused this. Please let me know how I can fix the same. Thank u 4 reading Regards & Wishes Zocon