One of the posts on the forum Is wmpnetwk.exe safe? How to remove a wmpnetwk error?
I suppose you might have the same problem as described:
I had CPU load issues alot are describing, also scanning folders for media would stop and never complete (which also immediately seemed to cause the CPU stress). It turns out it was a single video file WMP was having a problem with when scanning folders for media to share. I assume it couldn't read it properly and hung as a result. Try scanning for media in specific directories instead of the entire video library at once (luckily it was in the first folder I scanned :P ). Once deleted my CPU load issues were gone and all media scanned/shared properly.