10.9.2 2nd monitor fix

I called apple today 3/3/14

I got a great guy.

MacPro 2.66 Nehalem 8 core

I updated 5 days ago from 10.9.1 to 10.9.2 as soon as it was complete my 23" apple display stopped working (this is my main display).

I use an acer 22" as a 2nd display this continued to work. My hunch was that it was the update.

I tried switching the 2 montiors (no good).

I hooked up a 17" viewsonic and after 3 restarts it worked.

I tried hooking up the 23" again no good.

Then I tried a boot drive with 10.8.5 and the 23" worked again.

So it was the update.

I called Apple today 3/3/14 and got a great senior tech he had me do a "SMC"

I worked!! got my 23" back.

How to do a "SMC"

1. shut down completely

2. unhook the DVI cabel

3. unplug the computer

4 hold the power button in for 30 seconds then wait 10 sec to plug everything back in.

Good luck everyone