I didn't know vinegar could go bad....

[confustication]

I have a few food splurges- good salt, pepper, olive oil, and balsamic vinegar- So when I noticed that my balsamic had begun to grow, I was less than pleased.

I store it as I am 'supposed to' yet still, it has a film and stuff growing on top of it. Where have I gone wrong, and how can I prevent this in the future? I wouldn't mind if it was the cheapie white vinegar, but I really like my balsamic, and it costs more!

[cristeen]

Is it mold or is it scum or is it mother?

Is it possible it got contaminated at some point?

Is it real balsamic, i.e. expensive and made in Italy, or is it one of the many bastardized versions available in any grocery store? How old is it?