Pro tools 11 Record enabled problem

[Jeffrey Kubiak]

specs:
iMac i7 3.5
8g RAM
3tb ssd
Apogee duet 2 (correct firmware and install)
Pro Tools 11 (11.0.3) clean install
OS mavericks

Problem:
when i record enable a track it will sound fine but after 20-60 seconds the track will develop a lot of bit'like distortion. The only way to correct it is to change the playback buffer setting and then recording will resume fine.. but temporarily.. then 20-60 seconds later the distortion will return. It does this on any buffer setting (32,64,128,256,512), it doesn't seem to happen on 1044 however its impossible to record on that setting or on 512 because the latency is too difficult to deal with. please help me resolve this i spent over an hour on the phone with Apogee and diagnosed the Duet (doesn't seem to be the problem), and 20min ion the phone with AVID. I've ran the complete checklist on AVIDs website multiple times. PLEASE HELP!!!!