UNO digitalRead switching HIGH to LOW every cycle

I have a problem with my brand new UNO.

I'ts switching state from High to Low with every loop the UNO makes at all the Digital inputs when reading one of the pins.

Resetting doesn't help.

If only writing to the PINS there is no problem. But when I read from 1 of the pins the problem starts.

Any suggestions to solve this problem?

You are letting your inputs float. Reading Grumpy_mike’s page on inputs:
http://www.thebox.myzen.co.uk/Tutorial/Inputs.html

I had a 2k2 resistor connected on my breadboard as a pull-down resistor.

But I now try'ed it directly putting a 10K resistor directly on the board everything works fine.

James thanks for directing me in this way.