I'm trying to log in to my old channel 9 account using the classic log in (I know my username) but it keeps saying I have a Live ID already associated with the account... as far as I know I have a home Live ID and one for work... I've tried them both and the home one gives me this log in, and the work one asks me to create a new username for channel 9.

What can I do to find out which Live account my old channel 9 account is associated with?