A.) In windows explorer under ... Tools> folder options click on the view tab and click off the "hide names of known file types" otherwise windows will call all files associated with winamp to be winamp media files. be it wav, mp3, flac, shn ect.
B.) Flac is a form of compression inteded to LOSSLESSLY compress WAV files. (good) not mp3 and such which are already LOSSY compressed. (bad)
The golden rule that always applys. Garbage in garbage out.