Some files show 'H"4AP' (without the single quotes) as the filename in both the File Manager and when using, e.g., the Open command from various applications.

I've definitely noticed this with MP3 files. I'm not sure about other file types.

The file details show the proper filename in the "Name:" field.
osso_xterm shows the proper filename when using "ls".
The files play fine.

Any ideas why this is happening? It's quite common, but doesn't happen to all files.

Andy