Messenger does not sign in to inbox

I have an old windows 2000 laptop which has worked well. I use Messenger 7 to
access my Hotmail inbox. It used to require a simple click on the inbox link
and there it was. Now you get the hotmail sign in page with a message that
either my email or my password is incorrect. Adding my password lets me
through, but the point is, messenger and hotmail used to work seamlessly
together, so I avoided the sign in box. Reinstalling messenger made no
difference. Clearing the cache made no difference. Virus scans were fine.
Security info is fine.

Microsoft support has tried to help but can't think what's wrong. Anyone
else have an idea? Don't wish to upgrade to ie 7 as it affects my eyes. I use
6.1 which used to be fine.