Mouse maybe? Not sure

Am new here, not sure this is where I should be.  I have Dell 8400 with wireless keyboard and mouse.  In last few days, I use the mouse to get to an exact place for the cursor, but then, ALL ON ITS OWN, the cursor will move to the right sometimes as much as an inch.  Very hard to get the cursor to stay where it belongs.  Found out from friend, their cursor does the same on Dell also, but regular mouse & keyboard.

 

HELP!