A client of mine recently got this error:
Service 'Sdl.TranslationStudio.Api.ProjectManagement.IProjectManagementService' could not be started.
If you have this problem this is the solution:
Follow these instructions to fix the issue:
Close SDL Trados Studio 2009.
Go to the following folder on your computer (you may need to make hidden users visible to see this folder):
Windows XP users go to C:\Documents and Settings\[USER_NAME]\Application Data\SDL
Windows Vista/7 users go to C:\Users\[USER_NAME]\AppData\Roaming\SDL
Delete the file entitled Sdl.Enterprise.ServerConnectionManager.xml.
Restart SDL Trados Studio 2009.
SDL Trados Studio 2009 should now start successfully.