~TiddlyWiki works well in ~FireFox v1.0 and above. If you're experiencing problems, make sure you've followed the [[installation guidelines|Installation]].

When saving ~TiddlyWiki in ~FireFox for the first time, you can run into problems if you accidentally click 'Deny' on the dialog, and select //Remember this decision//.

To reverse the effects, first locate the file {{{prefs.js}}} in your ~FireFox profile directory:
* Under Windows you'll find it at something like {{{C:\Documents and Settings\Jeremy\Application Data\Mozilla\Firefox\Profiles\o3dhupu6.default\prefs.js}}}, where {{{Jeremy}}} is the name of your windows profile and {{{o3dhupu6}}} will be a similar string of gobbledegook. 
* On the Mac it'll be at {{{~/Library/Application Support/Firefox/Profiles/o3dhupu6.default/prefs.js}}} 
* On Linux you can find this file at {{{~/.mozilla/firefox/o3dhupu6.default/prefs.js}}}.

Open the file in a text editor and find the line {{{user_pref("capability.principal.codebase.p0.denied", "UniversalXPConnect");}}} and simply replace the word {{{denied}}} with {{{granted}}}.
//(Thanks to JonScully for figuring out this fix)//

Firefox users should be aware that GreaseMonkey can break TiddlyWiki. There's also a rather unpredictable FireFoxKeyboardIssue.