Arduino COM Ports

I have been working on stuff on my arduino and every 5-10min I will get an error saying my COM port is already in use or it is not found. I can go into device manager and disable and re-enable and that usually works. But now it is telling me to restart my computer every time I do this, this is getting very annoying having to restart every 5-10min. I am running Windows 7 and I have the right drivers installed for my Arduino Uno. Can someone please give me an answer on why this is happening.

what is connected to your Arduino? Is it possible that you can be dragging the USB voltage down?