I have no solution that works in every case, but often reducing the graphics acceleration will make Geometer (and other FLTK programs) work.
In your Control Panel you can click on the "Display" icon (which is sometimes under "Appearance and Themes") and under the "Settings" tab you can try either "Troubleshoot" or "Advanced" and reduce the grapics acceleration on your card. This may be just a slider for performance, or sometimes you can disable acceleration, as in "Disable WMV acceleration".
I am sorry, but so far I have not been able to figure out why this occurs on certain systems.
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