Sorry, I didn't make myself clear. The first mobo was exchanged for another of the same make and model. When the problem didn't go away the new one was exchanged for a different model by the same manufacturer.
I don't actually know that that was the problem. It was one of several things that were changed while we figured things out. There was another issue with an updated VIDEO card driver which caused other problems. I have an NVidia card (see sysconfig below) made by another manufacturer. Getting the new driver from the NVidia site was a problem. Once I rolled it back and got the driver from the Zotac site I was okay.
I'm not claiming to have the solution in your case--I'm just throwing out ideas, okay? But I did have the identical problem.
Windows 7 Ultimate x64, Reason 7, BIAB 2013
Intel i5 2500K 3.3 Ghz, Gigabyte ZX77X-UD3H, 16 Gb Corsair DDR3 RAM
OCZ 60 Gb SSD, WD 1 Tb Caviar Black 7,200 RPM HD
Zotac/Nvidia GeForce GTX 560 2 Gb, NZXT H2 "Silent" case w/liquid cooling
Presonus AudioBox USB, Behringer B2031A, JBL PSW D110 sub
Kennesaw (Atlanta), Georgia, USA