lcd spam pet feeder

Hi

I have made an automatic pet feeder but every time it feeds the 2 by 16 lcd starts spamming. weird random symbols run across the screen from right to left. (some $ some # some unrecognisable) I know the arduino code is still working because it still carries out the rest of the feeds. The motor that dispenses the food is a small geared motor which runs off the arduino 3.3 supply so could the problem be from power shortage. (the arduino is powered from a transformer not the computer)

Any help will be appreciated

Look here : http://forum.arduino.cc/index.php?topic=246703.msg1769642#msg1769642