I noticed possibly with the switching to 2015, that I'm having difficulty just opening a stp file. I guess stp is the same as step. At any rate I have my 3/d connexion mouse, & I do have Creo on my computer, although I seldom use it. When I try to open the step it's like SW isn't seeing it, then windows asked would I like to open recommending my the 3/d connexion or Pro E. It recommends those two, and lists a myriad of second choices, yet SW is not listed, so I can't point to it. At times when double clicking it, it will open it somehow in the 3/d connexion software, but nothing really shows up. How would I re-set my system so that SW is my default to open step or stp files, or at least get the file to come up somehow.
I open my step files directly from Solidworks either by clicking on the open icon or <File> <Open>. I don't go through an external program. I have noticed that I tend to get a lot of gaps or surfaces that need to be fixed before I can use the model. That is rather annoying. I never had that problem with NX.