Monitor no signal

I have lenovo laptop connected to a monitor when i start to type on the keyboard it often shuts down advising no signal and the power button starts to flash on the laptop if i press the win icon on the keyboard it takes me to log in page and i sign in again it often takes few attempts to get going again it seems ok just surfing the net its when i try to type and input the problem starts .
I am using a wireless keyboard but at the moment i am using the laptop keyboard, monitor not connected.

Any ideas.

Monitor no signal