Firewall blocking MSN/Hotmail

We are using ISA 2004 and a Sonicwall firewall. Now we can no longer access sites like Hotmail or AOL. We get Error code 64-a time-out error basically. Things worked fine before the Sonicwall. We have made rule exceptions for MSN.com and Hotmail.com and Passport etc. to no avail. Does Hotmail need a certain port open?