System error in Discovery Studio MCSS

Hi.  I'm using the multiple copy simultaneous search (MCSS) method for my research, however, I faced some problem when using it. 

Previously, a week ago, I went through with the tutorial and had successfully docked the fragments in the tutorial, where I followed the tutorial in,  "Tutorial'> "Receptor-Ligand Interactions tools tutorials"> "Fragment docking using MCSS". 

However, in this week, I tried to repeat the tutorial multiple times but the job failed, where it came out with 'System error" in the end. Besides, it took a much longer time to run before coming out with this error, which was more than 20 minutes. I tried on two different computers, each with 2.8GHz CPU and 3.4GHz CPU respectively, with multiple processors, but to no avail. As according to the tutorial, it would take around 6-12 minutes to finish the task. May I know in detail what may the problem be? 
 Thank you for your time. Your cooperation is deeply appreciated. Thank you