Updates:
A) I checked: yes it removes the title only when the "inaccessible" forum is visible from main page, NOT when it is under another forum, that is accessible. In that case it still shows the title... well it's better than nothing

Can someone help me out here? Maybe a loop checking the same thing for each subforum... dunno.
B) I'd like to manually update all the "lasttitle"... which query do I have to run in order to write all the "lasttitle", without having to wait for each forum to get updated with a new post?
Thanks for info, and thanks to PPN for the wonderful hack, which I'm trying with my VERY LOW knowledge, to improve a bit

(or make it worse, we'll see

)