My LCD screen shows strange caracthers after the print begins

Hi everybody!
I have assembled a Prusa Reprap printer and I am using a graphic LCD.
It was working very well, but I need to install Marlin 2.0.9, and after this, whenever the print begins, the screen stops to show the status, and begins to show starnge caracthers.
Does anybody know how to fix this?
Thanks!

It is probably electrical interference.

You must keep the lcd cables short as practical and away from all high voltage wires. Ie power, hotend, heated bed and stepper motor wires.

Thank you very much!
I will try this!