Hi Panos,

I'd have to agree with Olaf with power supply noise problems. Have you tried using a battery to supply power inorder to see if noise is coming in from your power supply? Power dips or jumps in the AC lines tend to cause trouble. The noise is probably telling the LCD module to receive a command and then it receives invalid (garbage) data from the noise. This could cause the LCD to stop displaying depending on what garbage was thought to be data. I recently saw this action while experimenting with serial communication. I used a 12V battery and the problem went away. You must have a very clean power supply to work with digital.

TTYL,

Dave Kaleta