I can get here, but no one at work using our proxy can seem to get to MSDN.
Our Network Administrator has no clue. He said if I could figure it out, he'd fix it. He thinks it is because the ISA Server is too old to understand Microsoft's newer HTML technology.
This is normally a DNS problem.
If it is just this site, it may be that the address to MSDN is registered incorrectly in a HOSTS file or the internal DNS.
For other possibilities see: http://forums.isaserver.org/m_2002006838/mpage_1/key_/tm.htm#2002006915
Are there any errors in the ISA logs? ISA should be able to handle these websites.