Wireless Mouse & Keyboard won't wake computer

I bought a new combo kit of wireless mouse and keyboard from Microsoft. The model is Microsoft Wireless Desktop 4000. I am using Vista. Somehow it looks that there is some problem with the combo the kit. But as it is a new hardware so I am bit doubtful to ask about replacement. There is a wireless usb controller. The keyboard and mouse turns of in between. Like they work for sometime and sometime they remain undetected. It looks that the usb controller is loosing power in between. This mostly happen when the system turn on back from sleep mode.

I am having the similar one and I am using it on Windows Vista. You have to re-install the drivers. To fix the issue try to use it on a different usb port. The one which you are using might not have enough power or simply it is weak to handle wireless signal. I had also found that this kit works a bit improperly on Windows XP. You need Vista for it or simply update your XP to SP1. You can test that on some other working system and if the same failed then it is much better that you go for a replacement.