mozilla stopped working

[M.Hockings]

I must admit that I don't know at what stage mozilla has stopped as I 
was doing a number of things with this one machine yesterday.  However 
now when I click on the mozilla startup icon at the bottom of the screen 
it appears to begin to start but then just ends without any messages 
displayed.  Is there a way to determine why mozilla is not starting, 
then I might have a hope about fixing it.

Mike