FLStudio doesn't decompress the wave files when you first install the program?
After some research the IL website explains that: "Many .WAV files included with FLStudio are .OGG encoded .WAV files. These files require the Vorbis ACM CODEC ...
FLStudio project files with FLStudio so that if you double-click on a .flp file, FLStudio will open automatically. NOTE: If you are using more than one version of FLStudio, use this option to associate files ...