SQL Server encountered error 0x80070422 while communicating with full-text filter daemon host (FDHost) process.
When trying to do a full text search with SQL Server 2008 I received this error:
SQL Server encountered error 0x80070422 while communicating with full-text filter daemon host (FDHost) process. Make sure that the FDHost process is running. To re-start the FDHost process, run the sp_fulltext_service 'restart_all_fdhosts' command or restart the SQL Server instance.
I was able to track this down to the SQL Full-text Filter Daemon Launcher service being disabled. Enabling and starting the service resolved the issue for me.
It is interesting to note that the service is set to a Startup Type of Manual but after a restart of my machine the service is started, so SQL Server 2008 must be starting it. Having the service disabled probably prevented SQL Server from starting it the first time I went to run a full-text search.
See this post (SQL Server encountered error 0x80070422 (FIXED)) for the same error message but I did not do all the steps he did (I just enabled and started the service).