no menu marlin

I have a mega with a sainsmart 12864 lcd and I also have a due with a radds lcd. Both are displaying same unusual behavior. Both have a display that show x y z and temp but when you click on encoder to go to marlin menu nothing happens. If I click on the encoder multiple times while I power up the Arduinos I will hear a click and get to the info screen then nothing happens. menu is frozen. I did try to find topics relating to issue but unsuccessful. Any suggestions would be appreciated.
ps I did hook up my sainsmart lcd and ramp 1.4 to a friends mega and the menu showed and encoder clicked since I originally thought I had a bad lcd
and I also removed all software (marlin and Arduino) to start fresh and its the same.

There is a setting in configuration_adv.h that specifies lcd refresh interval this is also used to poll the encoder. It may have a high default value.

Thanks TheTazzbot for the suggestion.... I installed the Repetior firmware instead... and now the menu and encoder are working on the Arduino due... I'll still try your suggestion for the mega..

Part of my problem was that I was not changing the eeprom number between 1 and 2, so maybe my updates to fix issue were not being applied.