Fucking great !!! 

For fucks sakes cant someone do something about it ?????

Psst.. More info plz.

PARDON ?? MORE INFO !!!!!?????
It's one of the most famous Error quotes on bandAmp, EVERYBODY knows "File is not a valid .mp3"!!
That and "You already have a song of that title",
Anyway how can I give you any more info about something I know fuck all about ? 
Try the Tech Support forum ;
http://forum.bandamp.com/Questions/10354.html
http://forum.bandamp.com/Questions/11442.html
http://forum.bandamp.com/Questions/6677.html
http://forum.bandamp.com/Questions/765.html
http://forum.bandamp.com/Questions/40831.html
http://forum.bandamp.com/Questions/17930.html
http://forum.bandamp.com/Questions/29056.html
http://forum.bandamp.com/Questions/34553.html
http://forum.bandamp.com/Questions/22425.html
 
Dont mind me, just doing the disgruntled bandAmp user thing,
cheers for the input dude, it is appreciated,
as my old Origami master would say "malfunctioning site no member has"!

Just want to add that uploading a song in FireFox usually ends up in an error at the top of my page.
But Internet Explorer (yuck!!!!!) has just uploaded my songs with no hastles!