Whilst on collaboration, this useful feature is still a bit buggy in some respects.

1) the error mentioned by me here over a year ago
http://www.firetongue.com/boards/showthread.php?8576-collaboration-error

2) I have noticed that sometimes for no obvious reason artists properly entered as a collaboration later appear decollaborated (if that word exists) eg Tom & Jerry as one unit. I then have to go back and separate them again.