Well, I did it. After much deliberation, I decided that using tabbrowser extensions wasn't worth it anymore. The extension is just too buggy and, although it's updated frequently, more bugs continue to appear. The code just tries to do too much all at once, which I believe is the source of the problem and the reason it's become practically unfixable.
In it's place, I've made the following adjustments:
Installed the tabbrowser preferences extension, which provides a few single-window tabbrowsing options.
Installed tab clicking options to allow control over what left- and middle-click actions on tabs and the tabbar do.
Opened about:config in the address bar, searched for "browser.tabs.loadInBackground" and made sure it was set to "true" to allow middle-clicked links to open in a background tab.
The result simulates most of the functions I used tabbrowser extensions for, while being a lot less buggy. I'll still miss some of the options, but I can live with having more control over how popup windows work, as well as making Firefox a lot more stable.
Incidentally, if you haven't already tweaked Firefox to uber speeds, I recommend downloading the tweak network settings extension, which makes Firefox about as fast as Opera. :)
geeky