[@multimediaex Participant 11 years, 8 months ago]

Now everything works for me. The only thing I made, I tested some backup plugins for wordpress.

[@multimediaex Participant 11 years, 8 months ago]

Hi, I have exactly this Problem. Visitor can see the forum, normaly registered user got an 404 page if they try to open the forum. The next problem is, that I, with admin rights can´t create any topics. I got the message “you don´t have rights to do this”. At the dashboard I´m not able to edit topics or replies, there is no point to edit this, it´s missing. In the profile I can see that I should have admin rights. This problem is since 4 days suddenly.
What I have changed at my comfiguration is the AddHandler, I disabled it, because I had problems with the registration of Buddypress. Perhaps this could have to do anything with the problem, I don´t know.
The plugins I use are:

AJAX Thumbnail Rebuild
Antispam Bee
AntiVirus
bbPress
bbPress Antispam
bbPress Moderation
bbPress Unread Posts
Blubrry PowerPress
Broken Link Checker
Buddy-bbPress Support Topic
BuddyPlug
BuddyPress
BuddyPress Activity Plus
BuddyPress Extended Friendship Request
BuddyPress Google Plus
BuddyPress Like
BuddyPress Live Notification
BuddyPress Media
BuddyPress Template Pack
BuddyPress Twitter
cforms
CodeStyling Localization
D64 LSR-Stopper
Download Manager
Flattr
GD bbPress Tools
Google Analyticator
Google XML Sitemaps
NextGEN Gallery
Optional Content Plugin
Semisecure Login Reimagined
Simple Local Avatars
Theme My Login
Uji Countdown
User Role Editor
Welcome Pack
WordPress Ping Optimizer
WordPress Social Login
WP CleanFix
wpSEO
WP Super Cache
WP to Twitter

I hope it helps, you are my last chance to fix this problem, I asked in a lot of other forums but nobody could help me.