Thanks for the reply.
This doesn't happen every time, and I'm not too sure what I might have been doing at the time. The script editor goes a bit awry when using the align text feature but Alex straightened me out on that one by using the |jc etc, commands. I've been trying different script entries to try and tie it down to a particular event, but, as yet no definite cause. Will post back when I've got something concrete to look at.