job gets aborted: how to fix errors: excessive distortion of elements etc

Hi guys, 

A simulation which I am dealing with is related to interaction of bodies by means of Abaqus/Explicit . Well, basically, going straight to the question, when I submit the job for analysis, it gets aborted and the following errors pop up:

1. "The elements contained in element set ErrElemExcessDistortion-Step1 have distorted excessively."

2 ."The ratio of deformation speed to wave speed exceeds 1.0000 in at least one element. This usually indicates an error with the model definition. Additional diagnostic information may be found in the message file."

Could anybody point me out what is the general remedy to solve these kind of problems, please, and in the meantime explain what does this sort of errors indicate, why they are normally caused?

P.S. 

I have attempted to resolve the problem by incorporating mass scaling (semi-automatic mass scaling with a factor magnitude of 20 and 10), but unfortunately the errors have not disappeared.  

Thank you very much beforehand!!!

Wishes,

Dmytro