PROBLEM

On Linux, you receive this error when trying to open up links from inside Thunderbird emails:

Error showing url: Failed to execute child process "/usr/lib/firefox-3.0.5/firefox" (No such file or directory)

SOLUTION

The solution to this was fairly simple.  Just create the link to firefox binary in the folder it was looking in for firefox

1. cd /usr/lib/firefox-3.0.5
   
2. which firefox
   /usr/bin/firefox
   
3. ln -s /usr/bin/firefox firefox
4. ll
   total 236
   4669475 lrwxrwxrwx   1 root root     16 2009-03-17 22:41 firefox -> /usr/bin/firefox*
   4669742 drwxr-xr-x   3 root root   4096 2008-12-27 20:02 updates/
   4669550 drwxr-xr-x   3 root root   4096 2009-03-17 22:41 ./
   4456449 drwxr-xr-x 291 root root 225280 2009-02-27 04:07 ../
5. #

This resolved the issue in Thunderbird and links could be launched from within emails.
 

Cheers!
Tom K.