Shouldn't be a size limit issue. I just created a bookmark with 1655 tracks in it along with a couple of smaller ones. My Karma had no trouble at all switching back and forth between them.

I'm guessing you're probably right about the corrupted track. Do you have anything listed on the Bad Tracks screen? Menu -> Settings -> Troubleshooting -> Bad Tracks. If so, delete them all from that screen, then try again.