Mac OS 9 Applications appear as "PC Documents"

On my iMac G3, and several other OS 9 computers, some applications simply appear as a "PC Document." The icon says "PC" in the IBM font. If I try to open it, it says that there is no application available. The same application appears properly as a classic application under OS X, but I want to fix this problem under OS 9. I'm trying to run the Mac OS 9 version of DOOM, but this problem keeps occurring. The file extension is not shown in the browser, but adding the ".app" extension doesn't work. This problem happens on every OS 9 computer that I own, which include, the iMac G3, the iBook G3 Clamshell, and the Power Mac G4 Cube. I cannot run certain applications, since they all think that they are "PC Documents." This happens with DOOM, Shufflepuck, Colony, and many others.