I have seen this problem reported before. 

My keyboard (iClever GK03 2.4G Slim Keyboard, Silver) bought it in November has started doing weird things. The keys I press have the wrong result (double clicks, no clicks, random ones). It happens from time to time, and it takes a time to disappear. Sometimes charging the keyboard seems to help.

What can this be? I would like to keep the keyboard proven this problem disappears, but it is a pity to have this problem so often (I have a PC, and I am unable to log in when this happens)