I am new to CE2000. Upon opening some mp3 files CE2000 seems to need a description of how to interpret the file contents.
What actually happens is actually well-known, and not exactly as Andy describes at all - it's not a CE2000 problem as such, and you can open the files if you know exactly what the format is. What's different between the CE2000 decoder and the WinAmp one is that the WinAmp one will still open an MP3 that has a corrupted, or even non-existent, header. CE2000 simply needs to know that the data it's been presented with
is an MP3 file, and the bitrate. Usually if you use 'open as', you can provide the information, with a couple of guesses. Effectively, you are rebuilding the missing header information.
If there's no extension on the file, or it has an incorrect one, you may need to append .mp3 to it - and I seem to recall that there is at least one other workaround for this too, involving RAW data.