I have this weird problem with a couple of continuous servos I bought from Sparkfun the other day (http://www.sparkfun.com/products/10189
The problem is that when I in certain situations connect the arduino via USB to my computer, Windows 7 starts looking for servo drivers! It doesn't find any, so it keeps searching, then disconnects, searches again, disconnects, and so on with a steady interval of a few seconds. Basically this makes the servos completely useless, as I cannot control them what so ever.
I have experienced this problem in two situations:
1. If I try to have both servos connected in parallel, using the same input pin.
2. If I try to change the servos pin values.
In order to calibrate the servos - and change the speed in general - I need the servos to take a variable input value. But it appears that every time I change the input value, the servo(s) disconnect, and Windows starts looking for drivers. The setup I have been using to provoke this problem is a simple potentiometer with values mapped to 1000-2000 microseconds, values which are directly written to the servo(s). I can confirm that the potentiometer values are in place, and that they are getting written to the servo(s), by the serial monitor.
This is a vital part of my project, and I really have no idea of where to start debugging this phenomenon.. So thanks for helping me out!