I had this problem. they emerged after the infrstructure upgrades of several environments (OTAP ) but none of the solutions on the internet worked. Fixed it using the following method.
Go to the central administration. Go to operations > Services on server.
Take a good look at the settings for
- Office Sharepoint server search
- Windows SharePoint Services Help Search
The stop these services one by one(all settings and information is lost, but will be rebuild after they are started again)
When stopped, start them again. you will be asked to re-enter passwords. Other settings are retained.
It can occur that at one of these services you will get an error telling you there already is a database , that is not suitable. the change the name of the database for that configuration. a new database will be created.
After i had done this, all my problems where gone.