We recently got a new iMac G5. It's running 10.4.4. We also upgraded to Apple's most recent Java fixes.
We have both Firefox 1.5.0.2 and 1.5 (on a back up HD).
The Extensions manager is broken. When we try to apply an extension we get a message that 'Software Updates' are disabled and we have to hit a button in the toolbar which then brings up Firefox Preferences, open to the Content pane.
There are no 'Software Update' blocking options on that pane or any other.
When you go to the Menu bar and select Tools and then the Extensions tool, the Extensions panel never comes up. A funny artifact on the current page is noted.
This is badly broken code or some weird conflict is going.
The Themes manager seems to pop up and work.