Help - IE6 under XP Pro won't access certain URLs

[dingster]

I have IE6 running on XP pro. I have an account setup as local admin and
renamed the built-in administrator account. In all accounts other than the
account mentioned above(all in the local admin group) IE won't access
certain URLs. If I click on it nothing happens - the IE icon doens't
animate, no click sound nor does a error page show up. If I paste those URL
in the address bar and hit enter nothing happens either. These URL works in
Opera in all user accounts. I've attached some of these URLs below:

This one works:
http://g.msn.com/0US!s5.31472_315529/HP.1001?http://msnbc.msn.com

These don't work:
http://g.msn.com/0US!s5.31472_315529/67.b3628/12??cm=LeftNav1
http://us.f100.mail.yahoo.com/ym/ShowFolder?rb=Inbox&reset=1&YY=80151

I've played with security settings under IE and even chose the lowest
security level. Nothing seems to help. Please help.

Thanks much in advance. - dingster