znobben, MSI has just recently released an UEFI/BIOS Update for a different P67 model with the following changelog:
- Fixed using Startech PCI Adapter card will result to no POST.
- Fix plug a PCIEx1 network card to all the PCIEx1 slots on the motherboard and no video occur.
The second line really looks like a fix for your problem.
That said, I am positive the same fix will be applied in an upcoming UEFI/BIOS Release for your board model. I don't know when, but it will probably be soon, especially if you contact MSI Technical Support and report the issue.