Help popping issue

[maxidud999]

hi ive had my eleven rack working with protools 11 just fine until I went a way for a while, I took everything apart and stored it, now ive come back ive got it all connected and when I arm the track for the er signal it playes fine but you can hear pops and scratches, ive tried changing the usb cord, and guitars and guitar cordes but still the same problem, also it works fine just playing the er throuth headphones not through the computer, I don't know what else to do, please help
thanks

[maxidud999]

also ive had a message that I never got before saying that communication with the eleven rack #2 has experienced and error. would you like to re-connect? could this be part of the problem