Did you move the entire folder "LiquidCrystal" contained within the .zip or just one of the files within? The entire folder should be moved.
Also, try removing or renaming any other LCD libraries you have installed. Both in you sketchbook/Libraries and in Program Files (x86)/Arduino/Libraries. Just drag the whole folder of the old one out onto the desktop temporarily or something.
It's possible the one you installed may be conflicting with the one that comes with the IDE. I may have had to do that with my project but I don't remember.
I used the auto install feature within arduino ide 1.0.5 according to the arduino website guide - and the library is called LiquidCrystal_I2C, which shouldn't interfere with the other, as it is named otherwise (According to my understanding)
The error of missing "POSITIVE" is indicating that the wrong library is being used,
which is due to the either the wrong library installed, or fm's LiquidCrystal library being installed incorrectly.
So I'm with snowman in that I would bet cash money, and lots of it, that there is a library
fm's LiquidCrystal library is not called LiquidCrystal_I2C
It is called LiquidCrystal
If LiquidCrystal_I2C was the name of the zip/library you installed,
you have installed the incorrect library.
The latest zip of fm's LiquidCrystal library is LiquidCrystal_V2.1.1.zip
If you installed the LiquidCrystal_I2C library
in order to use fm's LiquidCrystal library you will have to fully uninstall LiquidCrystal_I2C
The issue is that fm's LiquidCrystal library is replacement for the standard LiquidCrystal
library and there can be header file collisions with other libraries.
Essentially, fm's LiquidCrystal library can be thought of as multiple libraries bundled together in one library.
In reality it is one library but can support many different interfaces by using different constructors.
Because of this it can be a bit confusing because the constructor names don't always match
up with the library name.
For example in this case, the library name is LiquidCrystal but the constructor
name is LiquidCrystal_I2C
The zip image that fm created really isn't quite correct for using the IDE to install it.
I'd recommend installing manually.
You can install it in your home sketchbook/libraries directory instead of replacing
the LiquidCrystal library that came with the IDE
but you have to make sure it is named "LiquidCrystal" and that there is no other
LiquidCrystal IC2 library installed.
BulldogLowell's advice on the constructor is wrong for fm's LiquidCrystal library.
The constructor he provided was for the LiquidCrystal_I2C library which works differently.
So while both fm's LiquidCrystal library and the LiquidCrystal_I2C library both have a constructor
called LiquidCrystal_I2C, that is used to initialize the library for a PCF8574 based LCD backpack,
they are different libraries and use very different parameters in the constructors.
fm's LiquidCrystal library works with any backpack so it requires that you tell it how the PCF8547 is wired to the LCD.
LiquidCrystal_I2C library only supports a particular wiring so it does not need to now how it is wired up
but it may not work with your backpack.
The examples on Terry's yourduino.com site, referenced above are for fm's LiquidCrystal library not
the LiquidCrystal_I2C library.
You can only have one of these libraries installed at a time other wise, strange things can happen
since they collide with each other and the IDE can pick the wrong one or potentially even pick and choose different ones
at different points of time during the build process.
Which is why you see the POSITIVE error message.