Let's do one thing at a time...
I'm not sure how to find the version of IE
In IE6, it should be under Help>About IE
In IE7, thanks to M$ "improvement", you have to click on ">>", here:
Then Help>About
Windows Media Player cannot play the file because a network error occurred. The server might not be available.
In most cases, that would be web site problem, not yours.
You can post that web site address, and I'll see, if I can get there.
As for proxies, most likely, you don't have to worry about them, if you are a home user.
What type of connection you have?