on startup sometimes I get a plain blue screen instead of the windows 8.1 log in screen.
If i click on the screen I am able to log in to the desktop but the desktop image is broken up into panels whch shimmer.
I shut the PC down and back on again and get the same blue screen.
If I switch the monitor off/on the normal windows log in screen appears ok and I can continue normally.
I updates the bios from 0137 to 0147 but the problem still occurs intermittently.
I have now changed the mini DP to DP cable for a different one to see if that helps. Monitor is a Samsung Syncmaster SA650