I'm still back in the Dark Ages of SW2010, but you may need to tell Windows to open your SW files with the SolidWorks Launcher, rather than SolidWorks.
I'm on SW 2013, but I had this very same problem.
I can confirm that telling Windows to open files with Solidworks Launcher solves the problem. I simply had to right click on a .SLDPRT file, go to Properties, and change the "Opens with:" option to Solidworks Launcher. Did the same thing for a .SLDASM and .SLDDRW file and everything is back to normal!