@MassDude Confirm same and if you unplug mini DisplayPort from dock then there are no issues? except the fact the external display is not connected or connected directly to SP3 also no issues. Microsoft support contacted me yesterday to work through this issue, I made sure that they understood exactly what the problem was, also at their request a diagnostic package was downloaded and ran, the results of which have been uploaded back to Microsoft for review. I expect to hear back from them today at 13:15PM NZ time hopefully with information on cause and possible resolution. Will advise outcome
Actually, even if I unplug the external monitor from the dock, the same thing happens - first time just have 'Surface' displayed on the screen but nothing happens - 2nd time boots as normal.