Visual problem at Rhino for WIP viewport

[yotamshabtai]

HI, I regulatory work with Rhino 5.5.2 running on OS Mojave. I Have just instated Rhino WIP on my Mac and right at the beginning when I tried to use the Polyline, as you can see in the below image there is a strange visual problem at all views, I have also tied to make a simple box from the toolbar, but still the same problem, only when I used the shade and hide the wires the problem dispersers.
Dose anyone knows how to solve this problem?
Thanks.

[msmr]

Seems the same problem there:

Display error (from 5.4 prefs import?)

We made on a client an error by not updating to 5.5 and opening once - prior to installing v6 WIP. Now it seems the display prefs are totally out of control — this is how an empty file looks: [4%20prefs%20import] We already deleted the prefs, that was no help. Does anybody know where to delete / reset sth. to get a standard display setup? Thanks!