Callers notifed of a busy line

[dabble]

When a couple of users extensions are called, I hear the CP system message "user name is on the phone" then their greeting is played even though these users are not actually on the phone.

I have CP 5.0.

When I remove the check mark from the users properties within CP under callers notified of a busy line, it functions OK.

This has just started happening and only to a couple of users out of 1000.

My default is always to have callers notified of a busy line.

Has anyone else experienced this?

Thanks.