I have V5 and V6 installed and functioning fine.
I downloaded V7 WIP to play with Sub-D
Installed V7 WIP
Now my V6 desktop icon says “WIP” and when I open it I get a warning about V5 plugins not working in V6 WIP
There is another (new) icon on the desktop called Rhino WIP, but it also launches V6 WIP.
I think I found the problem - my V6 was originally a WIP, so it resided in a “Rhino WIP” folder. That seemed to gaff up the install for V7. I did a clean install of V6 and then the WIP and it seems to be all good.