Optimouse goes to sleep?

I have an HP9694c and recently installed a HP optimouse in the USB on the Keyboard. This came on line and worked fine with no special instalation required..(just pluged it in and it worked) The problem that I am having is that it keeps going to sleep..When this happens all I have to do is unplug at the USB and it comes right back on line again..I have tried uninstalling and reinstalling and it does the same thing.. sometimes it will work for couple day then again it will fail 2-3 times in a day. This happens when machine is allowed to go into standby.When restarted the mouse is frozen.. Suggestions Please..

Carol