get ping plotter, install it and ping HTC servers (free version is fine, addresses in the sticky in the Technical Support thread) Run it for a bit 10-15 mins. This will test your ping to HTC and see if your having internet troubles.
A dxdiag of your machine never hurts. (hit RUN, type in dxdiag, click ok, save text to desk top, and paste the first third of the info here)
Did you add any programs or change any settings since when you system was running and now when it isn't.