Have a look at the threads I mention in this one. http://arduino.cc/forum/index.php/topic,76395.0.html

From the interview:

"I was electrocuted once (well several times really but once of particular note)."

You can only be electrocuted once. 

Try to reduce this to a simple does it work or not problem.

If you want a simple test just treat the LCD as a serial device and print to it . Just hook up to pin 1 (TXD) and use the hardware serial.

If you don't know how to do a simple program for this read up on communications and there should be many examples on using serial.

P.S. I tried to load that 3wire for parallax but got errors.

LAYADA has a nice little tutorial on this.

http://www.ladyada.net/learn/sensors/cds.html

See this thread -

http://arduino.cc/forum/index.php/topic,76395.msg576985.html

Give it a try: Hookup a weak pullup to either pin 4 or 7 and plug the UNO into the USB.

 Does the display work after pressing the reset button on the UNO ?

It maybe that you are using either or both pins 4 ,7 in your setup. Avoid those and see what happens.

I think this has already been accomplished by this fellow:

 Don't know why all the troubles with getting the data but I do see where you are trying to grab the data on the falling edge E (enable pin).
 
I went and looked at what I've written for the avrs (I usually write in assembly and have just gotten into the arduino) and I also looked at the arduino library for the lcd's . The enable pin is usually held low when not writting to it. The data is placed on the bus then the enable is brought high for a brief period then it is brought low to write the data to the display.

If it were me I would enable the interrupt on the RISING edge of the enable pin.

If you are using an UNO (the newer version R2) to control a character LCD then AVOID using pins 4 and 7 in your definition.

What happens is when at first powered up if there is even a small 5volt signal (a weak pullup) present on those pins the UNO will hang.

So far from my testing it is just pins 4 and 7 that are affected.

On my LCD panels it seems that all the data pins ,and control pins show a weak pullup.

The reset button will work allowing it to reset.
 
If you need to use pins 4 and 7 then see the following thread for an all around fix to the problem :

http://arduino.cc/forum/index.php/topic,64256.0.html

Here is another thread dealing with the issue


http://arduino.cc/forum/index.php/topic,68477.0.html

Take a look at this thread.

http://arduino.cc/forum/index.php/topic,68477.45.html

Using pin4 or pin7 to control an lcd (data bus and control lines) causes the UNO to lockup.

Move your LCD connections to anything but pin4 and pin7

I'm going to start a thread in the diplay area about this.

You should have maybe posted this over in the display area - maybe the mods will move it.

Just did a little testing just to figure out a question I had. Like why didn't pin8 which is a non pwm pin not cause a lockup(see the thread mentioned for details).Also was it only confined to DB7 of the LCD panel because of its use as a busy flag .

Seems that pin8 (DIO8) is immune in my tests with the lockup. Just tried the top 4 bits DB4-DB7 of the LCD and they all cause a lockup.

Make sure the servo and the board have their grounds connected.

 This sounds a little like what was described in this thread.

http://arduino.cc/forum/index.php/topic,64256.0.html

Has the R/W line of the LCD been tied to ground?

 If left floating the LCD might think it should respond to the last command and set the not busy or busy (I think it's DB7 for the flag).

Redo your sketch to use pin7 and also set the led on the board to on to show the status of the program when it hangs.

When the board freezes  measure the voltage at pin7. If it shows high then that could be the culprit.

 Whenever I see the words  "9 volts" I think "is he using a 9 volt transistor battery"?

If you are using that type of battery then that won't work much at all. Not enough current.

Use a power supply that can deliver the current.

 Sorry if I haven't looked at everything again but it looks like you are moving along.

You mentioned something about the PIC and 4800 baud. If the PIC is only being used to drive the LCD by receiving serial commands then it would be easier to "steal " those than trying to dechiper the ones on the LCD.

It might help to at least define the model# of what you are interfacing to see if there is any data on it to help in this.
Pictures?

Assuming that you still need to look at the pins of the LCD then the LCD still might be driven by using the R/W function rather than by delays so by removing the LCD it would never be able to respond correctly.If you have gotten your program to trigger on the falling edge of E (enable) then I would at first see if the R/W (pin5) is being used. The R/W would be driven to the LCD so it does not to be in the circuit to test this.Just log that for awhile.If all you see are 0's then it's a safe bet that the programmer just used delays for timing. If the R/W is being used then the LCD must be in the circuit to be able to read anything (it could be fooled but that's another thing) useful on the data bus. So when R/W is High just ignore what is on the data bus.

I would also just look at DB4-DB7 (upper nibble) because even though it can be an 8 bit bus pretty much of the start up commands are  done using the upper nibble.

What you are really after is the initial sequence to see how this LCD is being driven.