I'm running Civ IV through steam on a mac. I have to press return after EVERYTHING. Like if I press R for a road to be built it will wait until I press return before going on to the next unit. If I press spacebar to have my warrior wait a turn I have to press return until it will go on to the next unit. Even if I have a unit move somewhere more than one turn away it will move one section then wait after that one turn for me to press return. 
This problem just started out of nowhere today and has never happened before. Any ideas?

This problem just started out of nowhere today and has never happened before. Any ideas?