Re: Topics Per Page plugin – new problem
You have a couple different problems. I have no idea if fixing the permalinks will fix the page numbers.
If you have an .htaccess in the Forums directory and there is a 500 error, then there was a problem with that file. You can verify the syntax of an .htaccess file here.
http://shop.alterlinks.com/htaccess-validator/htaccess-validator.php