I am running Windows 10 Pro and Solidworks 2017 x64 SP1.0

I can open files that are by default associated with Solidworks without issue.

I can do this both from within Solidworks or if I click on the file in my windows File Explorer.

From within a running instance of Solidworks, I can also open an X_T file from "File->Open".

But in my Windows File explorer, I cannot open X_T files.

I tried to use "Open with" ... but Solidworks is not listed as a default option.

So then I selected "Open With", browsed and selected the application:

C:\Program Files\SOLIDWORKS Corp\SLDWORKS

But Windows tells me:

"The program you have selected cannot be associated with this file type. Please choose another program."

So I tried associating it to the file "swShellFileLauncher" in the same location.

That seems to open Solidworks but gives me the error:

"An error was encountered while trying to open your file. Contact technical Support for a possible solution."

Can someone please tell me where the appropriate application to associate files with is located or what I am doing incorrectly?

Also,

I frequently use 2 instances of Solidworks at one on side by side screens.

So the solution will need to incorporate that ability.

thanks