Okay, so after mucking around I have managed to annihilate it. Here's what I did, with (a) the *hope* that it could help someone else and (b) the DISCLAIMER that I'm not a full-fledged expert in the inner guts of Firefox so there's the possibility you could wreck something:
1. Close Firefox.
2. An apparently key file for this that Contribute puts on your hard drive is npContribute.dll. You could search for it, but I found mine in c:\Program Files\Mozilla Firefox\plugins\. Delete it.
3. Contribute will create a folder with toolbar stuff in it in c:\Program Files\Mozilla Firefox\extensions\. The folder will be a long conglomeration of letters and numbers within curly braces. Mine was called {01A8CA0A-4C96-465b-A49B-65C46FAD54F9}, so look for that, but if you don't see one with that exact name, I suppose it might have a different name. (In which case, to find out which folder it is, double-click through each of the folders whose names meet that criterion. Within each folder will be a file called install.rdf. Open that with notepad or another text editor. Do a search or browse through for "<em:name>". That will tell you what plugin you're dealing with. If it's Contribute, you know you've got the right folder.) Delete the folder.
4. Browse to your Firefox "Profiles" directory (if you don't know that that is, look it up in your favorite search engine). There you should find four files called extensions.log, extensions.cache, extensions.rdf, and extensions.ini. Delete all of those. (Firefox should regenerate the latter three upon restart, and you are good to go. After deleting extensions.log, I do not see it anymore, and I believe it is overkill to nuke that one along with the others, but just to be safe I deleted it, too. You can probably leave it, but deleting it shouldn't hurt.)
5. You should be good to go! Restart FF.
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I will note that Adobe mentions that, at least for CS3, "Adobe Contribute CS3 toolbar plug-in for Firefox 2 and above is not getting un-installed when Adobe Contribute CS3 is un-install." (See http://www.adobe.com/support/documentation/en/contribute/cs3/Adobe_Con tribute_CS3_Read_Me.pdf)
I wish Adobe would resolve this, because that's kind of a serious issue. I love Adobe, I use CS3 almost everyday, and usually have nothing but good things to say about them. But if they know this issue exists, maybe they shouldn't have taken the FF plugin out of beta.
Hope this helps!
