Welcome to the forums! <img src="smileys/smiley1.gif" border="0" align="middle">
First I'd suggest grabbing my examples kit, it probably has some examples of platform movement as well as other things I've made, from here: http://ihadhope.blogspot.ca/2013/05/construct-classic-r2-examples-kit.html
Secondly, R2 is the right version to use, R1.2 is the last "official" release, while R2 has some fixes.
Not sure why it falls through, did you set solid to the floor, or just the player?
Also, try running R2 as an administrator, and make sure your DirectX 9 is updated (search DirectX Web Setup from Microsoft), and maybe try installing Microsoft Visual C++ Runtime 2008 (also free)