Deleting "Ghost" extensions from FireFox

Since updating Firefox to v1.5 I had a number of extensions that I couldn’t remove from the list because they were greyed out, this was somewhat irritating as I had the later versions installed too and so I was getting duplicates (see below)

Today I decided to see if I could resolve this, it turns out removing these ghost/incompatible extensions is fairly simple:

1. Close any instances of Firefox you have open
2. Navigate to %Documents and Settings%\Username\Application Data\Mozilla\Firefox\Profiles\*.default\
3. Backup the file: “extensions.rdf”
4. Open “extensions.rdf” in a text editor i.e. Notepad or TextPad
5. Find the line that starts with: <RDF:Seq RDF:about="urn:mozilla:item:root">

Below is a list of the extensions you have installed, I can only talk about my case but the ones that were greyed out extensions in Firefox were the ones that had a resource value of a URL rather than “urn:mozilla:item:{Guid}”. My file looked like this:

Simply delete these lines from the file, save it and restart Firefox. All should be back as it should be now…