Sounds like some funky driver issues, i've had similar things happen in teh past but theyre normally down to using multiple monitors or multiple graphics cards which i use both, i have no idea how it would be caused when your only using one of each. If i have both my monitors powered on startup i only see the bios on my second monitor, its the same thing for safemode too, not sure why it does it but it seems to want to send the signal to a certain port sometimes and nowhere else, i've had to just go through all my ports one at a time in the past till i found the one the signal was been sent to, half the time it was sending it to one of the onboard ports which led me to disable the onboard nowadays.