Same issue as laid out above.
Late 2013 rMBP with Nvidia 750m discrete graphics.
Swapped out DisplayPort cable for a higher quality mini-DP to full-size DP, issue still happens. No rhyme or reason. Occurs every couple of days.
I've used one of these:
http://www.amazon.com/Kanex-SnapX-Switcher-Control-Keyboard/dp/B005OTZ4IU/ref=sr_1_2?ie=UTF8&qid=1379039103&sr=8-2&keywords=displayport+switch
Worked pretty well.
http://support.amd.com/us/kbarticles/Pages/DrivingMultipleDisplaysFromaSingleDisplayPort.aspx
http://support.amd.com/us/kbarticles/Pages/UsingaBizLinkDisplayPortMulti-StreamTransportHub.aspx
About time.
Been looking for a solution myself.
Low power consumption, low cost, flexible, and they provide the performance numbers right up front to see if it is the right fit for you.
http://routerboard.com/RB2011L-IN
Picked up 4 for new office workstation with a hardware RAID-5 solution. Might not be as fast as an SSD, but overall storage, reliability, and redundancy beats out every other SSD solution for the same money.
They're also ensuring that if they need to support/troubleshoot the equipment, that the drives are not part of the problem. It would be impossible for them to test every single solitary drive combination, so instead they lock it out. That said, I believe that every device should have an option...
Sounds to me like this is a small shop with high data storage needs, whether simply the result of anticipated retention, or because they have a hodge-podge setup now....and that they have a limited budget.
All told, I heartily agree with all of the posts here saying 'need more information'...