A few people are posting problems with Linpus lite and firefox. You have got to try this.
Open 'File Manager'
Under 'view' tick show hidden files
You can then rename .mozilla to say .mozillaold
see if you can restart Firefox (you will have lost all your favourites etc though)
If it does not work, you can delete the new .mozilla and rename .mozillaold back to .mozilla
See this thread for more details.
It might be a different problem - but I doubt it... let us know if it does not work.