Input out of range error when trying to install

I am trying to install Fedora 18 on my server which is a dual core opteron system with a gig of ram and on board video. When I boot. I see "starting grub" then monitor reports that the signal is out of range. If I try to boot from a live disk, it goes out of range. What do I do? I've googled around and seen lots of people saying to change different config files but how? Also what is the right thing to do in what config file? The on board graphics is only VGA as an FYI and the monitor in a LG Flatron L1710S.

Thanks so much!

Greg