Just had the same problem. The only thing that ended up working was to transfer to us as IGES as detailed in the link below:
In Reply to alfonso medina:
An collaborator company is using SW 2011 x64 (64bit) Premium Edition with
SP4.0. and we are working part of their design. They started to send us STEP
files and we are unable to open those.
I found this piece of info:
and told the guys to export using STEPAP214 and not to include curves or
Is there any other advice that we can use to make this so called standard