I upgraded to MacOS El Capitan and to my chagrin my Kingston USB drive no longer works. I get some stupid "Unable to start DTXX application" or "ERR_COULD_NOT_START" error. Luckily, there's a solution--you simply have to upgrade the USB drive firmware using a Windows PC. Please see this and look closely at the FAQ section: http://www.kingston.com/us/support/technical/products?model=DTLPG3
Unfortunately, one my my older Kingston USB stick models is not listed, so now I have a useless brick on my hands. I contacted Kingston support, but they ignored me. Great. (That was sarcasm by the way).