BlueSky,
Hang in there; we're working on it. From what we can see, it is not a single board issue (I have seen it occur myself testing with both DX79SI and DX79SR boards). An RMA will not get you a board that doesn't have the problem, so that path is not the solution right now. We have a test BIOS with fixes for two separate bugs that were found during our investigation, but these fixes, while necessary, do not appear to address this issue that we are looking at (but, as we speak, these fixes are being rolled into BIOSs for other boards).
I will let you know where we stand once we sort it out...
...Scott