Well, you do have a problem. The SW is probably trying to drive the monitor at to high a refresh rate. If the monitor is not blown, there are a couple of things to try.
* The monitor Refresh may be able to be set using the Monitor control buttons. If not, look for a reset switch somewhere. That would allow you to boot into safe mode and turn off the Catalyst drivers until you can re-install em.
* Get hold of a second monitor (but note, it would have to be a better one than yours if the Refresh is set too high.
* Boot from the Windows Install CD-ROM. THat will totally bypass all driver loading from the hard-disk and will use the default refresh rates.
* Go into safe mode and set the Drivers to the default VGA, XVGA, or whatever. Then, reboot and reinstall the Catalyst drivers.
Basically, you need to get your system re-initialized *without* using the Catalyst Drivers. In safe-mode, you can un-install the Catalyst drivers. Then you would be able to re-install and proceed normally.
Luck.