Manythings.org/shuffle/ has a good explanation of how to fix the iPod Shuffle. It links directly to the sourceforge page of rebuild_db. It also explains why any reasonable person --such as a language student-- might find it useful to rebuild the database. I wish I had known about this sooner.
...is like a day without Linux -- and vice versa. I just spent an entire day and two nights locked in the s/cr/AAPL Cupertino BSD operating system, also known as MacOSX, after my Linux install got ill all of a sudden. That's about the longest time I have spent inside the Mac OS in 2010. The OS X icon previews are nice. I always liked the right-click-on-finder-window-titlebar-to-view-folder-hierarchy-and-go-up-a-level feature that appeared around 8.5 or 9.1 or something and which lives on, although there are better ways of navigating in Nautilus or Dolphin. Everything else is about the same as Linux. The Mac OS is a little like being locked into a corporate headquarters overnight, I figure. It's a successful company, and looks nice, but it doesn't feel like home, more like being in a corporate cubicle. Linux is more like being in your own home of your own design, made from a variety of prefab elements. In this analogy, Windows is a FEMA trailer, full of toxic formaldehyde and requiring powerful fans and ventilation to prevent a nosebleed, and possible death.
I don't know what was wrong in Ubuntu, but there was some glitchy window behavior, and instead of logging out and back in, I chose to restart. I think there was a kernel update or something that cued me to restart, and this may have followed the glitchiness, meaning something was not installed correctly. EFI, or rather, rEFIt, was OK, GRUB was OK, but then some text scrolled by complaining of a flaky scsi drive and dropping me into a Busybox shell, where I initially had no idea what to do. After returning from the Mac side (and running Disk Utility over there), things were basically the same, but I got a few seconds farther to an Ubuntu Studio splash screen before being asked to Repair, Continue, do something else, or More information, before that crashed and dropped me back into the shell again. This time I chose to "fsck" which did a number of repairs to inodes and whatever and allowed me to 
reboot into a repaired Ubuntu Lucid. I ran Update Manager immediately, and noticed one update called dmsetup addressing some bad code which the update offers to "take out back and shoot it in the head." That sounded good, so I did that. I may never know, but that could have had something to do with my system suddenly flaking. The take-away, if there is one, is to go ahead and fsck the system, if you think that might help.
