Notes on MAC (OS X 10.4.8) does not open URL's - Error: "unable to launch Program"

we have here a Mac (OS X 10.4.8) with Notes running.

URL links e.g. in email would not open, neither when we enter an URL address in the address bar in Notes.

Error: “unable to launch Program”.

I did try already to switch to Firefox, but same result. Can’t see anything wrong in the Location settings.

It works on other MAC’s …

any ideas?

Servus

Robert