See if any of this helps:

FIREWALL DEAD, or other network issues:
http://support.microsoft.com/kb/892350

MS antispyware tool disables Windows Firewall: Start>Run cmd [enter]
netsh winsock reset [enter]
Follow prompts and reboot.

The above fix only works on a machine that has SP2 installed. If it is
pre-SP2, use the WinsockXPFix.exe program.

For further questions about the MS Anti-Spyware beta, post in one of the
newsgroups set up specially for it:

- microsoft.private.security.spyware.announcements
- microsoft.private.security.spyware.appcompat
- microsoft.private.security.spyware.general
- microsoft.private.security.spyware.install
- microsoft.private.security.spyware.networking
- microsoft.private.security.spyware.signatures
- microsoft.private.security.spyware.onlinecommunity

These newsgroups can be accessed via NNTP or HTTP. To access these
newsgroups using HTTP, please go to the following location:

http://communities.microsoft.com/newsgroups/default.asp?ICP=spyware&sLCID=us

To access these newsgroups using NNTP, please use the following
information for your NNTP client (such as Microsoft Outlook Express):

- NNTP Server: privatenews.microsoft.com
- Account name: privatenews\spyware
- Password: spyware

NOTE: No password will be required via the HTTP link.

Malke