In the course of a private email discussion I found the following problem. Since this may be of general interest I repeat my findings in public. The discussion concerned possible OpenMP problems in GRHydro:
"The routine Hydro_Analysis_LocationSearch may return different results with OpenMP. If one component contains multiple maxima, then the last one is returned (without OpenMP), or a random one is returned (with OpenMP). However, if several components contain the multiple maxima, then the location of the maximum remains unset, i.e. at the value it had at the last timestep.
"I suggest to switch off OpenMP in this routine, to insert a check whether a single component contains multiple maxima and treat this the same as when several components contain multiple maxima, and to set the location of the maximum to a special error value (or to introduce an error flag) so that it is obvious when the routine fails."
-erik