hi there, i am having the same problem. updated driver, monkey, farm etc. on my ux2 (bought in 2008); then briefly got it to work with a microphone after hours of fumbling. lo and behold, i tried plugging in a guitar and it stopped working; i.e. i alternatively have no movement in the input level on the interface or the farm thingy says the sounds are not loaded. no sound in both cases, obvs. after trying to turn things off and on again for hours, i'm a bit peeved now to say the least. i have a macbook pro on yosemite, btw. grateful for any hints whatsoever! cheers from the north of germany.