Hi,
we have the same problem on our seven editseats running W7 and PrPro 7.2.2 on big Dell workstations. We just can tell you that it´s not a problem of the video i/o hardware. The drop outs are present under Matrox Mojito MAX, Aja Kona 3, BM Decklink and also without any video i/o, just using the onboard soundcard. Sometimes we can playback a 40 minutes timeline without any drop outs and suddenly we can´t play 20 seconds! We also tried the newest NVIDIA driver 333.11, but makes no difference. Also working without Cuda does not help.
We also have the same problem on HP Z-Books (W7/PrPro 7.2.2)
So I would say there is a big bug in 7.2.2!!