Keyboard and magic mouse erratic

Looking for assistance and very frustrated by totally erratic behavior of both my Apple bluetooth keyboard and Magic Mouse. I have tried different makes of batteries and other battery fixes found on Youtube such as adding some paper packing into battery compartment, but both these accessories are driving me mad. The most common problems are that it sounds like a key is being held down on the keyboard when no keys are being pressed (the only way to fix this is to turn off both the mouse and keyboard) and with the mouse the inability to select any pull down menu items - the pull down appears and then immediately disappears.

This is on a Mid 2011 27 inch iMac, OS X Lion 10.7.5

Any suggestions greatly appreciated!