It does not happen often but when it does the canvas in Max 6 refuses to lock (cmd+e) and the lock option is not available in the edit menu and all the buttons at the bottom of the canvas except the enable debug button grey out and I have to close the patch and re-open it. I get a little ding from my macbook everytime I try to lock the patch. I can open a new window and edit/lock that but when I click back to the funny window it still will not lock.
It is not repeatable - it only happens after a while of editing and moving things around. I think it happens when I am editing properties in the inspector and repeatedly opening and locking the canvas - not the inspector in the sidebar.
Max 6.0.3 MBP 10.6.8 13" i3 intel graphics