Nagymathe Denes wrote: > // compute rotational force > dMULTIPLY0_331 (tmp,I+i*12,body[i]->avel); > dCROSS (body[i]->tacc,-=,body[i]->avel,tmp); Is this the code that's intended to apply auto-damping to spinning bodies? I haven't actually read the code, but that could be one reason why something like this would happen. Cheers, / h+