Can't access Web Mail in IE6 Using Windows ME

My mother is running an older (P4) Gateway with Windows ME. She can connect
to the Internet (via cable modem), and can reach the sign-in page of her web
mail (she use both Yahoo and Hotmail). However, after typing user name and
password, she receives a message that the page cannot be displayed.

She has been updating Windows ME with Windows Update every time there is an
update. The problem developed suddently after one of the upgrades. She
tried to fix the problem by reinstalling Windows from her Gateway System
Restore CD. Same problem. It still runs ME and IE6, can access web pages
in general, but cannot access web mail.

The email accounts are good -- she can access them on my computer.

Is Internet Explorer possibly to blame? Windows ME?

I'm not sure why Internet Explorer wasn't rolled back to the original
version (I believe IE 5 or 5.5) when she ran her System Restoration. Would
uninstalling IE6 result in a rollback to a previous version or wipe out IE
entirely (which I'm not sure is possible)?

Does anyone have any ideas? I know a lot about computers (not necessarily
expert, but a fair amount), so I get tasked with fixing things, but I can't
seem to handle this. I would appreciate any help anyone could give, at
least pointing me in the right direction.

Thank you. Kathy So