Invalid ID, invalid forum specified

[victis]

The problem is that when user tries to enter a forum, error is being displayed:

Invalid Forum specified. If you followed a valid link, please notify the administrator.

Sometimes you only have to refresh and error is gone but now many users of my board are experiencing this problem and they're getting frustrated...

It happens randomly, started like few days ago. What can be a solution to this problem?

Edit: Changed the thread title to more specific.

[Michael Biddle]

What version of vBSEO are you running and what are the contents of your .htaccess file?

[victis]

I'm running vBSEO 3.2.0.

Anyway, the problem was caused by memcached, which I have activated some days ago via the vBSEO panel. I have changed it now to eAccelerator and now everything works perfectly fine.

Why has it failed to work properly with memcached?

My config was as follow:

localhost:11211,5
Use Persistent Connections: No
"Time to live": 3600
Retry interval: 15
Connection Timeout: 1
Minimum Object Size To Compress: 1