Yes! That worked. The directories listed by utnubuuser were the ones I needed.

I booted into recovery mode, just in case it was a bad idea to change desktop settings files while the desktop was actually "on."

Connected to my backup drive, switched directory to the backup of my home, copied over the three directories using
Code:
cp -a .gnome2 /home/quix/.gnome2
and so on. In my case, .metacity is a subdirectory of one of those, so I didn't need to do it separately.

In the process of doing all that, I noticed that my home dir was 100% used! No wonder I was having trouble. Turned out that .thumbnails/ had gotten huge, even though I'd told Nautilus NOT to cache the damn things. (I'd run into that problem once before.) So it was nothing to do with Audacity. The original problem was that the partition had filled up and I hadn't noticed.

Thanks for all your help folks! I couldn't have done it without you and I really appreciate it.