I have a 9.0.1 suite installed and the latest Max4Live. When I try to edit a M4L device, the front of it goes translucent white, and after a while I get the Max message window appearing - no patcher. After this, there's no sound from the Max devices, and Live is very unstable.
The following appears in the debug view (I read this could be used in another post)
 Max: starting db update (schema version 6.1.0)
 startup call: translation_getpreferredlanguage
 code: en, name English
 startup call: eventreporter_init
 startup call: eventcontext_end
 Max: unable to open FilesCycling
 Max: unable to open 74Max
 Max: unable to open 6.1Max.exe
 Max: unable to open /nopaw
 Max: unable to open /sms
 Max: unable to open mfl64_610
Which suggests that something is amiss in Live - it seems to be passing an unquoted file path, or similar (MAX is installed under the default c:Program FilesCycling '74Max 6.1... etc
I have raised a ticket with Ableton but wondered if I may get a better answer here - Max standalone (in demo mode) works fine, and doesn't display these errors.