Error message in Firefox

I'm using Firefox 2.0.0.7 and I noticed that clicking on a link that's in the thesaurus (so in the csv file) gives this error message (alert):
"It seems as the script can not connect to the server. Please check if controller exists by URL controller.php"

Links do work fine though.

This message also appears on the demo site http://www.cmsdevelopment.com/thesaurus/ by clicking the IntelliTXT logo in the IntelliTXT thesaurus. (and it's not because the image is missing :-)

Error message does not show up in IE 7 and in Opera 9

Any solution?
Thanks,
Aiko

Found a workaround for the problem by removing the alert from the thesaurus.js file but that would not be the correct way to solve the problem I guess....

Script still works fine !!

Cheers,
Aiko