If the version number is 7.1.1.071 then it's MMSIM71 (Update 1), so fairly recent. You're using it with IC5141 (for the environment).
restart=yes was unlikely to help, because it should restart the DC anytime the DC is impacted by whatever you're sweeping.
Running 64 bit wouldn't help either. Rather oddly that was picking up MMSIM62, which is an earlier version. And all that command does is check that it's going to run in 64 bit mode.
I suspect something strange must be going on - it could well be a problem with the setup, but I think the best bet would be to contact Cadence Customer Support at
http://support.cadence.com and then they (we) can investigate in more detail, hopefully with access to your data to take a proper look.
It's not a symptom I've seen, though.
Regards,
Andrew.