iPod says "Do Not Disconnect", but does not show up in ITunes or desktop

I have a fifth generation 80 gig iPod video, which I purchased about a month ago when they were on sale because of the new generation coming out. This morning, I connected it to my PowerBook G4, and while the iPod realized it was connected and popped up the "Do Not Disconnect" screen, my computer doesn't seem to have reached the same conclusion on connectivity. Hence, I can not disconnect the stupid thing safely...

I've searched apple's FAQ, and am not getting anywhere. Does anyone know what happened here?

Thanks!