this can happen if this hour is open or being viewed on another terminal somewhere, or possibly a PC was disconnected from the database by a network error.
You should try to find an alternative method of playout (CD, MP3) then make sure Myriad and AutoTrack is closed on all terminals, look in the computer management of your "Server" and see the open files list to see if the database is stuck open anywhere.
If it is close the open files.
Next perform a database compact / repair from the Emergency Recovery tool, do this for all your databases, Myriad Station Log, AutoTrack and Directory.
Then fire up AutoTrack and try removing.
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