I have a problem with the modification Premod when you need URL rewriting and wants to enter the forum or topic, I received a message "Sorry, we did not find any such file."
At the first forum and the mod works on the second forum on the same server is not working.
Can it be the fault of the address? address for forum looks like
-http://www.myadres/forum/
Forum is located in the directory /forum

I'd bet on an .htaccess and / or phpBB Server and Cookie settings issue.

If you have more than one phpBB install under the same domain, eg at least one in a sub-directory, you should use the "more options" option of the .htaccess generator and the the "alternate location" one to generate an .htaccess meant to be used in the sub directory (as the red message would then tell you to).

Because it's quite easy to mess up if you are trying to merge the two .htaccess into a single one in domain's root.

++

I use "more options" and works, thanks