Could be spammed fake/corrupt files.

Try playing them with either of these players: (a) Vox :: The Lightweight Music App for Mac OS X :: AleNofx (plays almost every audio type you could think of), or/& (b) VLC (which is predominantly a video player but plays most audio types you will come across). If the files do not play with either of those players, then unfortunately they are fake files.

There's a few different type of fake files. (i) One are deliberately corrupt, (ii) the other are files linked with advertising links or viruses. Virus thread: Typical virus spam file sizes - Make a note of them (click on blue link to see). Gives an idea of file sizes to be wary of when you see them.

For the deliberately corrupt files, see mp3 Bit-Rates Versus File Sizes (click on link). This is a technique that's not so easy to learn to recognise. But comparing bitrates & file sizes is a major trick to discovering which ones are spammed corrupt files.

From your description, they sound like fake files. Probably have windows viruses imbedded or links to the internet that take you to some site to download a codec which is actually a virus, else just gives an advertising link. If you tried to play them in QuickTime, they might just do that, attempt to connect you to the internet. Don't do it. Vox & VLC will do not read internal hyperlinks within a file so you're safe there.