Dropouts using ChannelStrip/Rev-x and some third party plugs

i just bought a mr816csx and i get dropouts when combining internal dsp effects and some third party plugs.
e.g. i have 2 audio tracks. i use the channelstrip (s) on one and virsyn reflect/fabfilter-q/ratshack (one of them) on the other channel.
When selecting and opening the effect section of the track with reflect, dropouts occur. everytime i select the track or open the effect section.

i updated all drivers and firmware. i run cubase 6.5.4 on imac 4x2,9 i7 mountain lion.
i tried isolating the problem and it also occurs with only the steinberg/yamaha driver and reflect/fabfilter are installed.
i tried changing the buffer size and everything mentioned in the “optimizing your computer…” page.

can anybody maybe try and reproduce the dropouts?
the steinberg support couldn´t help but i sent them the project. would be good to know if it´s a problem with my configuration or if it´s a bug in the drivers…
thanx guys.