No, i believe it's a problem in your lilo.conf.
Edit your /etc/lilo.conf -- first become root (type "su") -- then, at a console, you can use "vi /etc/lilo.conf", or in a graphical desktop, use "kedit /etc/lilo.conf" Look for a line starting vga= and try making it vga=788. There may be multiple lines, look for them all.
Afterwards, run lilo to reinstall your bootloader.
If you don't use lilo, ignore this