Buffalo wrote:

remove your monitor in device manager.

When I do that (in fact, I just now did it) there is no choice
on setting a refresh rate, not even default or optimal.

Display Properties now doesn't even have a monitor tab and no
refresh rate choices in the Adapter tab.

Maybe you need to at least have the default monitor installed.

Go to Control-Panel and select "add new hardware".

Hit "next" twice.
When asked "Is the device that you want to install listed below",
select no, then hit next.
When asked to search for hardware, select no, then hit next.
In the hardware selection list, select "Monitors", then hit next.
The right-hand window will show (standard monitor types) (leave it
there).
The left-hand window will show models. You should see a list of
"Super VGA" modes showing resolution and refresh. Select the one that
matches the resolution and mode you are looking for.

You should then see "to continue, click finish". You shouldn't have
to re-boot.

When that window goes away, bring up the device manager and see if
there is now a monitor listed with the resolution you chose
previously.

On the ATI control panel, you should now see the same monitor type.

You might have to restart to see it.