[CentOS] Error when clicking on link

Good Morning--

Since installing CentOS4 the other day, I've had trouble with 
Thunderbird 1.02 when attempting to click on a link within an email. 
Rather than opening a tab in Firefox 1.0.4, I get an error message:

"Error showing url:  There was an error launching the default action 
command associated with this location."

When I installed CentOS, I left my home directory intact so I would have 
to re-option apps I had already been using.

Has anyone else had this problem...and found a cure?  I did check the 
archives, but didn't stumble upon anything useful.

Thank,
Dick

-- 
Pithy saying goes here:  (future).