Opening .iges and .step files from Windows Explorer via double click nets me an error shown in the picture. I've been through the whole repair process, been through the clean uninstall, re-install, remove registry entries and everything. Still didn't fix it. I've had this issue before with 2013 and that did fix it. Now that I've updated to 2014 the issue is back.
The issue is evident with SP0 right off the DVD, as well as SP2.0, and SP3.0. I can't shake it.
The work around is to File/Open in the SW window, but it's obviously less efficient and convenient than opening directly from windows explorer as it should.