Tversity slowing down Windows 7!

This has never happened before. When I first installed Windows 7 and was using Tversity to stream videos to my Xbox, it ran just fine; no slowdowns, nothing. Now that I recently put a fresh copy on a new hard drive and installed Tversity on there, the system lags like crazy! At first, I only noticed that the playback on the 360 was sluggish on some videos, but I soon realized that the sluggish performance was because somehow, the streaming was lagging my laptop big time, and I don't even know what I should do or need to do.

I'm streaming videos from an external hard drive, if that helps. I'm not sure if the drivers for the hard drive were installed correctly and if that's what would cause the lag.