Bluetooth mouse problem?

 i have a dell travel Bluetooth mouse which needs to be reinstalled every time i have to use it.even if my comp goes into sleep mode, on restarting i again need to reinstall it.isn't there a way in which my comp would connect to the mouse as soon as i keep it besides my comp.i have Studio 1555 laptop with windows vista ultimate 32bit on it. thanks a lot. please reply.thank you