How are you plugging in the LCD? Are you removing/attaching the 4 pin i2c cable while the Arduino is powered?It could be creating a power glitch on the Arduino board.
R/W is connected to pin5 aka P1.
I have gone ahead and done all the library related things you have listed. As I mentioned, I had replaced my sketch-LiquidCrystal_I2C directory with the contents fm's library. I have now deleted both the sketch and the IDE LiquidCrystal directories and unzipped (the non-MAC) files into an IDE directory called LiquidCrystal. It seems to be working. During detection now, the backlight is on as well as all of the LCD dots. Is it supposed to be like that?
I'm glad the instructions on installing this library are clear as mud. LOL.
The unit is an Arduino Uno and genuine as far as I can tell. (I ended up with a counterfeit one, but am not using it especially for debugging). The crystal says 16.000, I'm assuming MHz.
When the LCD powers up before it is initialized, one row of characters on a 16x2 LCD will be "blocks" with all pixels for each character position turned on. The other row will have its pixels off.Once the LCD is properly initialized all the pixels will be cleared.The guesser sketch attempts to initialized the LCD and then print the constructor on the display.
On power up, I see the backlight and one row of dot on, the other off. When the guesser searches and finds the LCD, the LCD is on with all dots on both rows lit. After I click send, the LCD blinks 3 times and then the constructor appears with the backlight on.