Check Your Batteries
If you have rechargeable batteries in your mouse, try checking the battery status. In Windows XP, click Start and Run. Type in main.cpl and then click OK. In Windows Vista or Windows 7, click Start and type main.cpl into the Search field and press Enter. The Mouse Properties dialog opens. If there is a Wireless tab, go to it and verify the status of the battery. If there is not a Wireless tab, try recharging your batteries or the mouse itself, if it is rechargeable. Use a different outlet or port than you typically use to charge the mouse or the batteries.
If you do not have rechargeable batteries, replace those in your mouse with new, alkaline batteries. In fact, if you do have rechargeable batteries and the problem continues even after recharging, try using fresh alkaline batteries. Your rechargeable batteries may not be holding a charge or the charger could be defective.
Make sure batteries are correctly inserted and that there is a complete connection. Certain rechargeable batteries have shorter posts than alkaline batteries, which can cause a faulty connection.
After following these steps one at a time, you should be able to get rid of your Microsoft wireless mouse blinking red light and get back to work.
Open the battery compartment. Check for and remove anything that could be obstructing the batteries' connection. Look for corrosion as well and remove it, if possible.