I have seen this issue posted several times around these forums with no acceptable solution given. So, I felt compelled to make an account here to tell you about this, again.
I am running Maschine 1.7 in Mac OsX Lion. It works 100% of the time in control mode as either a stand-alone application or as a VST inside Ableton 8.25. I have no problems whatsoever with Maschine itself.
My problem arrises in Midi mode, particularly while controlling Ableton Live. It will work for a random amount of time and then abruptly stop working. Maschine itself will still function in control mode, I just lose control of everything in Ableton. The fact that the Ableton template works initially with 100% functionality and Maschine keeps working afterwards leads me to believe that I have everything set up correctly.
It is hard for me to ascertain precisely when and why I am losing control of Ableton because I am usually working in Maschine mode for a while, I'll only notice when I switch over to midi mode to adjust something in Live and get no response.
Oh and also: I have my takeover mode set to pickup but it just does whatever the **** it wants. Meaning, sometimes it works other times I get abrupt spikes in values.