try running an nslookup on hotmail site:
C:\> Nslookup www.hotmail.com > c:\hotmail.txt
Name: www.hotmail.com
Addresses: 64.4.53.7, 64.4.43.7, 64.4.44.7, 64.4.45.7
64.4.52.7
access-list 110 deny ip any host 64.4.53.7
access-list 110 deny ip any host 64.4.43.7
etc...
etc..
Funny,
I am trying to open those sites for my users, and I think you may have solved my problem.
Thanks,
-paul