For the analysis engine, em, if the frequency is too high, then the analysis is done at a point where the response of the circuit is already changing. If the frequency is too low, then precision errors occur which produce faulty data. An algorithm is provided with your software to automatically calculate this frequency which has a 95% success rate.
Analyzing at such a low frequency may lead to precision errors which corrupt the output data, so results of this analysis option should be scrutinized carefully.
You should also be aware that if current density data is being calculated as part of an analysis, it is not provided for the DC point.