I don't play the Simpsons every day, but have played it quite a bit on different versions of MAME throughout the year with any trouble.. What version of the software are you using?
I don't think I have had a problem on DMAME .62-.73. You might want to update your version or if you are completely up to date, back off to an older version. Someone here might be more familiar with the driver for that ROM but I know some roms will "break" in updates, only to be fixed later (The sound on NBA JAM was one of these that I remember).