Flickering is a bug - refer to richard

however - it only happens in the following conditions:

A)
If you have either output 1 or 2 selected as 'mix all layers with fx' but no layers assigned to mix/ouput 1 or mix/output 2.

B)
If you have a mix window open, but not layers assigned to it

Solution:
Either assign a layer to the mix/ouput and put the intensity to zero
or
change the screen mode to 'no output'
or
click on or move any of the HUD windows.

This bug happens in all versions back to m301
It is due to a screen buffers not being erased correctly - when no layers are active in a mode which draws in full screen

Richard may have fixed this - contact him directly if an issue - most of the time its not...

S