But have you looked at WMP's Tools > Options?
There may be options there that will prevent WMP from searching the internet for additional information about these tracks, eg I found in WMP, "Download usage rights automatically when I play or sync a file".
I can't say whether any of those settings will help, but they may.
I keep running into this problem with Windows Media Player in that it thinks that the music I ripped from my CDs came from Napster, and therefore I don't have the right to play it. (I had the same problem with Rhapsody.) If I reboot my computer then sometimes I can play the song. None of my music came from Napster. How do I fix this and prevent this from happening in the future?