Start up issue in Win 7.

Just recently my start up has been pausing causing the mouse cursor to disable for about thirty seconds.  Then I I hear two of the sounds that you hear when adding or disconnecting a USB.  Then all works fine.  The only hardware that I have altered was to do away with a Logitech headphone and add a Logitech speakers and Sub.  It has a single entry into the speaker receptacle and not a USB.  It only happens if I shut down the computer.  Does not do it if I do a restart.  It would seem to me that one of the USB items that uses computer power is hanging up.  Hope that makes sense.  I am hoping that I can eliminate the problem by removing each of the devices one by one to see which one is the problem. I would sure appreciate any suggestions and see if anyone else has experienced this.  

I am using a Jetline Sytem (specs can be provided) and running P3D v4.  Use all Saitek controls to include rudder, pedals and throttle quadrant.  ASAv4 and a Netgear wireless USB for internet.  

As always, responses are appreciated and grateful for your time.