I just had the same thing happen, Andy, on a new machine I just spent 2 days building from scratch without sleeping, making me have to scrap the whole thing and start the build all over again from right from the basic OS install.
There is no way that I know of to install the free version of this software without it installing around 1,000 registry entries, making switch or some other member of the "NCH Software Suite" registered as the default program for audio, video and other file types, and choose it's own file associations.
While one can uninstall the Switch Sound File Converter program, it does not perform a clean uninstall and leaves fragments of the NCH Switch installation littered all throughout the registry, as you found, as well as not removing any of the entries for the "NCH Software Suite" at all, apparently.
After running a very thorough 3rd party software uninstall program that does a thorough scan of the registry and file system after the application uninstall to identify and delete any overlooked entries to ensure a complete and thorough uninstall... even this program could not locate and remove hundreds of entries left corrupted throughout the registry; entries for source locations; entries for command shell associations; entries for file associations, and so on.
As I had installed a version I downloaded sometime last spring or summer I believe, I thought perhaps I'd download the most recent version and try installing that to see if it behaved any better. To my amazement, it did the same thing, both on the install and uninstall routines; and I went through the same process all over again, spending about 4 hours running registry cleaners, 3rd party uninstall programs, and manually going through the registry again, removing hundreds of entries and file associations that were left on the machine after the uninstall... entries I had already spent about 4 hours manually locating and removing previously . I had been thinking I would save myself another 48+ hours of having to rebuild the entire machine all over again.
But having put in a good solid 8 hours of attempting to clean my machine myself, hoping I could continue with the build finally, it finally became all too clear that I would not be able to clean the registry and would not be able to put the machine back into having any kind of integrity or get it to a place where I would have any faith in its reliability and was going to have to face the fact that I was going to have to start over from scratch all over again.
Now, I know exactly why this situation has occurred, and I'll tell you why right here -
it's because of two reasons -
1. The Packagers were lazy and simply didn't ensure their uninstall routines were packaged properly. When they do, the only thing left on the computer are entries in the MRU folders, and some temp files that were not tracked by the install routine.
2. They either did not have anyone doing SQA (Softwre Quality Assurance) testing for them, or those who were doing the testing were so inexperienced and lacking in understanding of how to test application integration and backout processes that it essentially wasn't even done.
I spent over 10 years as a Senior Engineer in both the Packaging and SQA areas, supervising teams in these areas as well as performing these tasks and establishing standards and practices for those companies, and I have never seen an application be released to "production", or to the public that was in as bad shape as these two NCH releases were.
Now, a ray of light that I saw was when I noticed they have a deal going on right now where they are offering a licensed copy or Switch Sound File converter for $19.95. Generally, licensed copies of software have no "suites" or "adware" included with them, and to simply not have to deal with all the garbage being installed and left all over the machine might have been worth the lousy $20 or so. Especially when I'm contemplating spending in all likelihood another 72 hours to get this machine fully rebuilt, imaged, and up and running in pristine condition again.
First of all, I couldn't find any information that a licensed copy was indeed "suite free" and would not cause the harm to my machine again that the free version did. Then, using the program heavily at times in the past (from installs that did not do what these last two installs have done, I should say, I thought I'd try to make the purchase going on the theory that the Packagers and SQA team usually tends to put more effort into the paid versions. But rather than $19.95, when I got to my PayPal account for some reason I found it was going to cost me $27... and still with no guarantee it was not going to attempt to perform the "side by side" install of the Suite for "install on demand" purposes, as well as for the hope of future sales by keeping their range of products before me on my machine where I would see it from time to time.
All in all, it's a terrible situation, and they are damaging peoples machines with these poorly packaged and tested programs.
I don't know how computer savvy you are, or what your resources may be, but I would be looking at performing a System Restore, re imaging the machine using a restore disk, or saving all the data you can and having your machine rebuilt if your registry is as thoroughly trashed as mine now is.
I actually got excited when I saw someone else had just experienced the same thing that I had, but as I kept reading I found you discovered the same thing I did, our machines are mucked up, and the amount of mucking up is far beyond restoring to a condition the machines were in prior to the NCH install spreading all its muck around...
In my case, I had actually meticulously created restore points after every program I installed over the 48 hours or so I had done solid installations and configured iand tweaked along the way. My error was, having never run into any problems with Switch in all the years I had used it in the past, I had not anticipated running into any problems going forward and thinking it was a "safe" install, I just happened to decide to free up some disk space and deleted all the restore points I had so meticulously saved before I discovered the wrong file associations and the flawed uninstall routine, and so on....
So, I have no choice but to do a complete rebuild as I jumped the gun and removed those restore points too soon.... I also have some older versions burned to CD I'm sure, which I'll see if I can locate, but there's no way I'm putting the download they're currently offering, or the one I had downloaded last spring or summer back on this machine... there's no way I'm going through all of this again.... I need a sound file converter program and there are others out there I can use like SUPER, and some others if I have to.... but I'm not going through this again...
