Wavy Characters on 16x2 LCD

Hi everyone, I've an issue where after 10 seconds, my display develops a wavy interference(?) when running a basic timer ( lcd.print(millis()/1000); ) that seems to settle down after a couple minutes. The first few tries with it worked ok, so I'm a little stumped as to what would cause the problem.

I'm an Ardu-nub at the moment so not sure what information to include to assist... sorry...

Any ideas would be a huge help though.



Can you post your example sketch and maybe an image of the problem?