I've checked and the buttons don't appear to be solder bridged or anything. And the buttons are far enough apart to not likely be fat fingered. But, it also happens if I right button to that screen, also.
But it appears to be resetting the program, ie running setup() again.
With my current configuration, if I press the reset button on the Freeduino the LCD goes "one line" on me - known issue. This doesn't happen, so I'm not quite sure it's a full on restart, but like it's just running setup() again somehow. I went looking through the Guino code, looking for a possible hosed pointer or something, something where a memory address is getting trounced. Nothing jumped out at me. It could be a memory corruption or allocation/deallocation issue within the arduino program code. A bit far fetched maybe. Does it not happen for you?
__________________
|