You really should upgrade to 0.9.1. Here's a thread about re-enabling urls in comments:

http://forums.b2evolution.net/viewtopic.php?t=5564&highlight=comment+url

Ok, I will do that. Can I just copy the files from the dawn release onto my server or is this more complicated to upgrade?

Make a backup of your current files and your database if you can. You shouldn't have any problems with the upgrade, but if you do you don't want to lose the data forever. Then upload the new files and when you try to log in it will tell you that the configuration hasn't been run yet. That's fine. Let it run. Feed it the info for your database and tell it to do an upgrade installation. Then you'll be able to log in with your normal username and password.

so I can just replace all the files and copy my old changed ones over again?

And to come back to the topic: The user ARE able to post links and <a href tags into their comments put urls like http://www.google.com are not automatically changed to

<a href="http://www.google.com">http://www.google.com</a>

After you've run the installation script to upgrade the database you can merge your changes back in. Depending on what type of changes you've made, you can copy entire files or remake your changes by hand. Once you're done with the upgrade we can revisit the comment problem.

ok, I did. I had also remove the disallowed <a>-tags in comments but there is still no automatic url conversion to hyperlinks. =( Some kind of "Auto Links" for comments

Look also here:

http://forums.b2evolution.net/viewtopic.php?p=31347#31347

Still no idea?

I finally understand what you're talking about. The autolink renderer plugin is not being applied to comments. Here's a fix. Open /b2evocore/_class_comment.php and find this part:

        function content( $format = 'htmlbody' )
        {
                $comment = $this->content;
                $comment = str_replace('<trackback />', '', $comment);
                $comment = str_replace('<pingback />', '', $comment);
                $comment = format_to_output( $comment, $format );
                echo $comment;

and make it look like this:

        function content( $format = 'htmlbody' )
        {
                $comment = $this->content;
                $comment = str_replace('<trackback />', '', $comment);
                $comment = str_replace('<pingback />', '', $comment);
                $comment = format_to_output( $comment, $format );
                // YaBBa's hack to use renderer in comments
                global $Renderer;
                $renderers = explode( ".","b2evALnk" );
                $post_renderers = $Renderer->validate_list( $renderers );
                $comment = $Renderer->render( $comment, $post_renderers, $format );
                // end hack
                echo $comment;

I tested that on my blog and it worked fine for me. Be warned that this will make your blog a more attractive target for spammers. That's why I'm going to remove this hack from my blog right now. That's also why this isn't really a bug. autolinks are disabled in comments on purpose. Once you confirm that this fix works for you, I'm going to move this thread to another forum. Credit for [url=http://forums.b2evolution.net/viewtopic.php?t=2700]the hack[/url] goes to ¥åßßå.