We have two 64 bit Windows 7 Ultimate machines that are exhibiting the same problem. The default gateway is normally set to a cisco router. When configured with the cisco router as the default gateway, Internet functions fine, except no Microsoft web sites are available (msn, microsoft, technet, etc). All non microsoft sites come up without any problem. Non 64 bit windows 7 machines and non windows 7 machines configured with the same default gateway are not having any problem accessing any web sites including microsoft sites. We also have a ISA server in the environment and when the default gateway is changed to point to the ISA server instead of the cisco router, the 64 bit windows 7 machines are then able to access all sites including microsoft sites. This has me baffled. There are no known restrictions on microsoft sites (or any other sites for that matter). Why would the 64 bit Windows 7 machines restrict the Microsoft web sites when using the Cisco router as the gateway, but have no problem when pointed at the ISA server? Note this problem started when the cisco router had a problem and had to have the power cycled. All other operating systems (including a 32 bit windows 7 machine) are behaving normally regardless of which default gateway is being used. Any ideas or suggestions on how to resolve this would be appreciated. We prefer to have the default gateway pointed to the Cisco router as opposed to the ISA server and that had been working for quite some time without any problem. No idea why the problem cropped up all of a sudden. Thanks for any help you can provide.

The problem went away after upgrading the cisco router firmware. Strange that it came up all of a sudden ... but it seems to have fixed the problem.