Hello,
Whenever I try to open the manual, either the one that installs with the game or the one you can download separately, I get an error telling me that my computer can't read it. I know for a fact that my computer can open PDFs, so I'm assuming there's some kind of problem with the file. Figured GOG should know.
-Gammix

Nevermind. For some reason something went wrong last time adobe reader tried to automatically update, and all the files were deleted. My computer was trying to open with Microsoft Works instead. =P