garage band midi issues

I upgraded to Tiger and now I cant get garage band to work. I keep getting this error msg:

GarageBand has detected a MIDI timeout. Please restart your computer, then relaunch GarageBand.

If the problem persists, update the drivers of all connected MIDI devices (including audio drivers with MIDI functionality) to the latest version. For instructions on removing older drivers, consult the manufacturers' documentation.

I am not using any midi devices and none are connectd to my computer, I just want to record a simple a capella vocal with a metronome. Can anyone offer me some guidance?

Thanks