It sounds me like an incompatibility problem between the nxt core dlls used by Flamingo and the ones used by Lands. This is: Flamingo has loaded an old nXt core version while Lands needs a newer one. Try to update Flamingo nXt/nXt 5.0 to the latest version.
If this is not the problem. Can you send us the crash dump file (to "email@example.com") ? You will find it next to the 3dm file (I think), or in the desktop, during the Rhino Crash dialog. You must rename it before closing the dialog since the it is going to delete it at close.