An update to my Hardy LTS desktop caused my nVidia drivers to puke again, and for some reason they refused to reinstall. It's all related to having installed this system first as a Gutsy install, and using the nVidia drivers downloaded from their website. Every time there was a kernel upgrade I'd have problems, and it started getting worse with package file conflicts recently.
My hard drive had also gotten a bit small for me, so I decided maybe it was time to go ahead with a fresh install of Jaunty (which I'd downloaded just before the drivers went wacko) and take the opportunity to throw in a new hard drive.
On my first install attempts the Jaunty CD would simply drop to a BusyBox console prompt and never install, without giving any indication of what the problem was. I did a bit of googling and found that this could be caused by a crappy SATA control chipset on the motherboard. I then wasted the next hour attempting to update my BIOS without Windows, a floppy drive or a USB stick. I finally was able to run the BIOS update by placing it on a CF-II camera card and using that. Unfortunately there was no improvement.