I have an sql server 2008 installed. there are about 6 databases created and running on this server I often get message like "SA account is locked out"

is there any specific reasons for this account being locked out?

is there any other place I need to check the reasons ( I checked the eventviwer but could not get much information)

Edit: i found this information in teh eventviewer backups. Is this the cause?

SQL Server failed to communicate with filter daemon launch service 

(Windows error: The service cannot be started, either because it is disabled or because it has no enabled devices associated with it. ). Full-Text filter daemon process failed to start. Full-text search functionality will not be available.