Probably because the Santy worm used automated Google searches to find phpBB boards to infect; several months ago Google disabled the ability to conduct those sorts of searches in an attempt to halt the spread of the worm.
I have now done the changes you said.. what actually happens? what have I done? How can you check that the changes have been done on the web site? I have changed it in the Php file and uploaded it, but I don't seem to se anything different.... Can you? www.xbox-talk.com
My network of web sites: xBox-Talk.com - Balando.com - NewRoomTalk.com HumorHour.com - Ordigno.com - Playword.info
Oh sorry, probably should have explained. Basically, if you are not logged in it won't generated a session id (sid) on the end of the urls, which is why a lot of forums don't get indexed. Since a bot will never be logged into your forum, you don't need it. If you hover over your forum links, notice that the s=03298203942039482 is not attached to the end of the url anymore. Now, login and you should see it again.
If you want, you can start to experiment with things like mod rewrite now. All I did for my forums was use mod rewrite to make each forum a static php page. I haven't bothered with doing it for topics, I don't think it's worth it with the new version coming out soon.
For this, I used the code below in an .htaccess file.
rewriteRule ^viewforum([_0-9a-z-]+)\.php$ /viewforum.php?f=$1
I would test this out on a server that's not live if you have never messed around with mod rewrite before. Then, you just begin to look for places where viewforum.php?f=1 would be written and change it to display as viewforum1.php instead. For example, you would look through the index.php phpbb file for statements that will pass the links to each forum and rearrange it so it will use the new static page.
seems like recipher has given you a detailed answer and absolutly working, i just visited ur forum and no trailing sessions for visitors thus google as a visitor will be able to index you forum.
Ofcourse you have to understand that doesnt mean you will get ranked or u will find your pages ranked suddenly !
Now resubmit your pages to major search engines.
For google you can check if it indexed ur site using :
and you will see how many pages it returns ( should return a lot when it re-indexes it )
Meanwhile - resubmit and wait ( try phpbb seo as adviced ) and work on with it !
Just a reminder, you don't have to resubmit your pages to Google if it already indexed though. All you have to do is get links to the main page, or sub pages, so I would highly recommend doing that instead of trying to submit each page to search engines. I would look through the Google search I posted above for other advanced modifications like page title etc. It takes a long time to start doing well in search engines, especially Google, so don't expect it to be immediate.