Does your son have a separate User Account on the PC?
If so, and if there are no plans for your son to use your computer again, you may want to delete his account, Start > Control Panel, User Accounts, Change Account, select the account to be deleted, then select "Delete the account".
If that is not the case, then does your email software hold the Hotmail email account for your son? You haven't said whether you access Hotmail from a browser or through email software, but if it is through email software which do you use? If it is Outlook, or Outlook Express you may be able to delete your son's account from the Tools > Accounts menu.
I hope this helps.
I am running XP Pro on my notebook and have enabled hibernate. On restarting XP after hibernation, when I get to the log on screen, I have a message telling that I have a number of unread mail messages and how many programs still running. When I click on the unread mail message, it will inform me that I have a number of unread mail in my son's (who does not live with me any more)various hotmail addresses.
He has deleted these letters but I still cannot get rid of this recurrent unread mail messages.
Can anyone help shed some lights as how to delete this unread mail messages at start up please.