this is due to is loosing focus, edit the gps skin (might be external_gps.skin) look for something like A01,0,0,800,500 and stick a C01,0,0,800,500. Make sure the C01 numbers match the A01 thats already there, this will stop the flashing
Why does map monkey screen go blank and then return when you use the bottom skip track button in road runner.
If you use the map monkey controls to skip a track it doesnt do it, but if you use the buttons at the bottom from the road runner skin (brushed metal, latest one) it refreshes the map monkey.
CDR is correct on the reason.. but if you follow the GPS FAQ PROPPERLY MM will embed in a way that it will not "flash" (go blank) no matter what you do. If you have this issue, it is very likely the information on the MM screen isn't showing propperly either. Just follow the FAQ to fix it.