In the past 6 months or so, I have been having a issue opening ProE .prt files.  It gives me a error that it is not a valid part file.  I have always been able to open ProE files into Solidworks in the past, but something has changed.  Either in ProE or Solidworks.  I am receiving .prt files from multiple customers with the same error when I try to open the files.  Has anyone else seen this, or have a solution for this?