I'm a 64-bit user and as many 64-bit users do I installed 32-bit firefox to get plugins like flash, java, and mplayer working. Unlike most 64-bit users I went the extra mile and replaced 64-bit firefox with 32-bit firefox. BAD MISTAKE - Now all my gecko based applications are brocken. Apparently yelp, epiphany, and all other gecko applications depend on the DEFAULT firefox to work.

I have removed firefox 32-bit and installed it in a seperate directory. Now I'm trying to the 64-bit (default) firefox. I'm running into problems. When I try to install the "firefox" package in synaptic I get this error message:

The funny thing is that the j2re1.4 package isn't installed and /usr/lib/mozilla-firefox does not exist:

Sometimes 2 or more packages contain the same file or directory, as it's difficult for all the maintainers to know what package should have what file/directory in it, so that's what the error is all about.

apt (synaptic, adept or any other package manager) won't fix this as it's dpkg that's giving the error, but it's nothing the CLI can't fix.
If any other error comes up then try with "--force-overwrite" as well as "--force-overwrite-dir"

Have a look in the man page for dpkg in the "--force-things" part.

Turns out all I had to do was install j2re1.4 and then install firefox. I feel rather stupid right now. Anyways thanks for your help.