Model geometry might be changed -Simulation

Hi,

i am trying to do a study about a quite complicated assemble.

But every time i try to run the simulation i get this error (see attachment).

even before running there is an error icon at the simulation tree. and when i press "what s wrong? .." i get the other error.

I have no idea how to fix this nor what it means. i tried rebuilding the assembly, closing it and reopening it, ...

but nothing works

SolidworksSimulation