This fix now works partially for me, but still I must delete cookies WITHOUT restarting the browser as I did it before.

I mean, I can go directly to the forum form a fresh start but if I leave it and try again later on from another website the error message apppears again. Then I delete the cookies and I recover the forum access with no need to close the browser and open it again as I did previously to change the code. (Mac OS, IE 5, NS 4.7 and 2 diferent machines and IP)

Regards,
Niko