I assumed it was the standard Material Editor but yes, the problem occurs whilst being used from the Max plugin. Essentially mouse clicks are disabled and I suspect there is a graphics card issue as well.
sorry Bogdan for not being clear - I am talking about your second example but the eye dropper in the MXED colour wheel window not the one in Max's own editor - BUT only when called from the Max plugin, if MXED is started independantly the dropper works fine.
Max's own material editor is not affected (your first screen grab).
I saw similar in Cinema plugin. When I run MXED via plugin, colour picker freezes the MXED and picker does not pick Ctrl+Alt+Del is only working solution I have found...