[gh0sth@cker]

I'm guessing that the reason behind this is the ATIP check. Briefly, every CD-R has something called an ATIP which contains info on length, dye, manufacturer etc. Pressed cd's (originals) do not have an ATIP. So with newer protections the game checks to see if the cd contains an ATIP, and if it does then it obviously won't let you play it. The problem with the protection is that only cd-writers (mainly) can read ATIP. So if a user plays the copy in a normal cd-rom then it will play fine because ATIP cannot be checked for.
In Alcohol's options there is an option called "Ignore Media Type" which is selected by default. This will allow you to play in a cd-writer (which is what is happening for you). Clone CD also has this - called "Hide CD-R Media"). You could always download Daemon Tools (search Google) which is a free program that can provide virtual drives, emulate protections, and hide cd-r media.