Strange bug in software.

Currently running a Catalyst 4 10-layer setup with three projectors as "one screen" output from the Hog3PC. Show was programmed on HOG3 fullsize. And I have found the following bug:

When removing color fx (that is, changing to something else or going back to default) "trans black" a flash of a colour wheel image appears on screen for split second. This occurs even if all layers are turned off or another layer above the one I am changing is on.

Anyone got the same problem or something similiar with color fx?