Inspired by another post, I am reminded of some difficulties I had with playing Mp3s.
Specifically - the MP3s would work just fine on my main computer, but when played on another computer most of the time some tracks would play and others wouldn't. I couldn't seem to nail it down to one particular operating system or codec suite either.
In the end, I eventually (and accidentally, to an extent) noticed that some of the source MP3s were in 48000 khz - which in some respects isn't a standard frequency. I decoded the MP3's to .wav and converted the sample rates from 48,000,16-bit,stereo to 44,100/16/s and the problem vanished. I was able to use either VBR or CBR [url="http://en.wikipedia.org/wiki/Constant_bitrate"](variable/constant bitrate)[/url] and each would work fine. It was just that the 48,000 bps was causing compatibility issues.
Traditional standard frequencies
22050 khz all either stereo/mono and 16/8 bit
CD Audio is 44,100, 16-bit, stereo. DAT tapes pushed this a little at 48,000 khz but didn't really manage to catch on, and the original MP3 specification tends to bug out with anything other than the standard frequencies.
I don't know what the case is with OGGs for music, but it's a pity because OGG is an excellent format, (I just hate the name).