Hi,
Follow the suggestions and check if this works fine.
Method 1
You may run the Hardware troubleshooter.
Open the Hardware and Devices troubleshooter
http://windows.microsoft.com/en-US/windows7/Open-the-Hardware-and-Devices-troubleshooter
Method 2
You may follow the steps from the article.
Troubleshoot response failures in wireless keyboard or mouse
http://support.microsoft.com/kb/838398
Method 3
If the issue still exists, you may contact Microsoft Hardware support.
Microsoft Hardware