SQL Server 2008 Full Text Index Never Seems to Complete
I finally found the cause of my problem! 

I tried for months to track down the issue, but finally gave up, disabled automatic change tracking, just manually initiated incremental population and moved on with my life.

Meanwhile, there had been another nagging error that I was having trouble tracking down.  Periodically the website would throw a DB connection error:


  Cannot open database "XXXX" requested by the login. The login failed. Login failed for user 'XXXX'.


It turned out that both of these problems had the same solution.  All I had to do is turn off a database setting called Auto Close.  To do this, just right-click the database and click properties.  In the properties window select Options and set "Auto Close" to false.



As soon as I disabled Auto Close, my DB login issues went away and the automatic change tracking worked perfectly.

Thanks again for everyone's help.  I appreciate it!