The computer is turning off the mouse to "save power."
This is an error in the operating system setup. It is not just your computer, it effects lots of computers.
You may need to use another mouse to adjust these settings, if the computer keeps turning your USB mouse OFF.
click system properties
click device manager
double click on mouse and other pointing devices
right click on "HID compliant mouse"
left click on properties
left click on the power management tab
UN-check the box that says: " allow the computer to turn off this device to save power"
check the box that says: "allow this device to wake the computer"
REPEAT this procedure for the USB, located on the device manager list. turn OFF the power saver for ALL USB ports, one at a time.
REPEAT this for the keyboard also.
Click OK, close all windows and restart.
Now, you should be working.