Rhino WIN keeps resetting tab layout

From carefully crafted two-level tab layout back to default (no crash happened). Infuriating.

Hello -assuming you use Rhino maximized, please try:
‘restore’ Rhino (not maximized)
Resize it to be as large as you can on the screen.
Arrange the tabs & toolbars
Maximize Rhino
Close and reopen.
?

Does that work any better?

-Pascal

It happens only once in a while, usually when other session is open, struggling doing something.