I know it's way too late to answer this question, but I'll just post the solution that worked for me, in case someone runs into trouble again in the future.
I tried using genymotion's own adb tools and the original Android SDK ones, and even purging and reinstalling adb from my system, but nothing worked. I kept getting the error:
adb server is out of date. killing...
cannot bind 'tcp:5037'
ADB server didn't ACK
*failed to start daemon*
error:
So I tried adb connect [ip] as suggested here, but I didn't work either, the same error came up.
What finally worked for me was downloading ADT, and running adb directly from the downloaded folder, instead of the system-wide command. So adb devices will give me the error above, but /yourdownloadpath/adb devices works just fine for me.
Hope it helped.