Redream Trouble

Have had Redream (a Sega Dreamcast emulation) running on my mini for a little while now.  It works awesome.  Well until the other night.  When I load up the racing game I like.  Very screen had this weird blocking thing going on.  Tried another game and the same thing.  Messed with one of the settings and seemed to fix the second game.  Decided to uninstall the program, then re-install it.  That didn’t help.   Not sure what is going one.  May be the game files got messed up some how.  Going to have to look into this more.