I think the dissconnect was using trying to use garageband. The music browser was not happy.
You were using a file created with GarageBand? Have you saved your GarageBand projects with an audio preview? Perhaps you should save the project again.
I popped over and created a new library and slideshow promply crashed when I tried to add one. I then went into the Aperture_Presets_Slideshow...and the window popped open for a split second and also caused a total crash.
O.k. that leaves out your current Aperture Library. But does it work from a different user account? If not, then you would have a system wid trouble with Aperture and audio, and need to reinstall.
But if it works from a different accout, we'll know that some setting, plug-in, login item only used in your current account is causing this.