Im running Windows 10, P3d V4.  Never had any trouble with A2a, PMDG etc.. but with this Carenado SAAB (which I can't wait to fly...) I get stuck during the install.   After putting in my email and serial number it then asks which simulator I want it in.  That's when I start to see a problem.  The choice p3d is there and I can click it but I do see a strange rectangular shaped white box covering something.  Then the next screen after I choose p3d it wants another selection and appears to have a browse option.  Once again I see the white box but now I cant choose anything, it won't open a browse window or anything.  Then the installation just hangs and I have to use task manager to get out of it. 

Have tried with Firewall off, ran install file from desktop.. from the drive my P3d is located...same result. Anyone have any clue as to what is wrong?...I have sent a support ticket to Carenado but I have no idea how long they will take to respond and I kinda wanted to try this out this weekend.

I have exactly the same problem having just downloaded the program. Extremely frustrating.

I have reported to Carenado too but in the meantime found a workaround.  The problem occurred on my flightsimming desktop machine but I also have a less powerful laptop for travel. I copied the install file over to the laptop and ran the installer without a problem (pointing the installation to an old copy of FSX on that machine). I then manually copied the files over to the P3D folder on the desktop - some of the Carenado specific files locations were a bit of a guess so I didn't know how it would work.

I reran the install file on the PC desktop and although I got the "flashing boxes" on the "choose simulator" and 'location choice" pages, this time it suggested the correct location for the P3D install and the "next" button wasn't greyed out. Effectively it reinstalled over my manual install and put the previously guessed at files in the correct location.

Not elegant but the result is a fully functioning S340 and first impressions are extremely positive.  It will be interesting to see what Carenado's answer is.