I had a similar problem at one time and it was just that an update sp2 had not made the right config in the registry. I followed the instructions and was able to get word to operate. All it was a 0 to 1.
The main mackey from the ISP shop eventually came out and said that Windows is corrupt.
As everything else works and only the internet part not, we've concluded that something might have been corrupted on the tcp/ip stack.
Seems they are going to reinstall windows to fix it. hahahaha
You don't know how happy I am that it's not me. With all the apps and stuff this man has on his PC, it's more than a days job, for nothing.
Phew, glad to have dodged that one.