here's some cranial output for you, I am putting myself to the fullest possible use, which is all I think that any conscious entity can ever hope to do.
I wish this could be more concise but it's hard to know exactly the problems, on what "view" etc. Plus, when Vista was new, it was often considered to be the most reliable operating system ever made. No Vista computer had ever made a mistake or distorted information. They were all, by any practical definition of the words, foolproof and incapable of error.
Some time passed before some errors were admitted. But we're not talking about the past.
Hope this has the bones of the solutions for you.
"I've hidden them but they won't go away"
assuming something like after you: clicked "edit", then "preferences", then "instruments" tab.
In that view, I can only hide demo instruments which I haven't purchased - but the ones I have purchased, can't be hidden and there's no "uninstall" button right there. I suppose it makes some sense, if after-all, you paid good $s it's logical to keep "uninstall" buttons away from the main view. You'll probably have to contact support to remove paid instrument packs (from your licence - and a new activation might be needed - I just don't know about that)
BUT IF you only want to remove the free KIVir pack, for the sake of that mission.. Well, it's rather difficult to define. Perhaps I'm just projecting my own concern about it. I know I've never completely freed myself of the suspicion that there are some extremely odd things about this mission. I'm sure you'll agree there's some truth in what I say.
In that instrument preferences view, at the bottom right, there's a link which reads:
"The PTQ files are stored in this folder" - the "this folder" part is the link.
Click that, it'll open your file browser to the relevant "Add-ons" location - then, you can just select and delete the file you don't want, close the file browser and maybe restart Pianoteq - although I would caution against any rash decision such as this Dave, I mean Peter, plus I don't know why, but I'm a..fraid that uninstalling always makes me think of the song Daisy ;-)
Anyhoos, maybe that text link on that instrument preferences tab might want to become a button in future versions.
There is no question about that. I can feel it.
However, if it's just about organizing personal tweaked saved settings or esp. sorting to your liking:
Click "Help" and then click "Manual" or online, go here:
Managing and sorting presets
[That same info is in the file named "pianoteq-english.pdf" or whatever language your chose when downloading Pianoteq, in the "Documentation" sub-folder where Pianoteq is installed if you want to access it outside Pianoteq.]
It gives plain info with clear diagrams for sorting your view of:
"different pianos all over the place, nothing's in any sort of order"
Hopefully it's easy to get more organization to your liking being able to make folders with logical names etc. mainly from within the interface, no need for hunting around in a file browser too often.
Also, maybe you have lingering issues from having more than one version of Pianoteq installed side by side, maybe sharing various system folders. Multifarious issues possible - especially if copying your settings files into different folders. Each version may reset your changes on startup etc (haven't tested for this problem with Pianoteq and might vary between OSs)..
Whilst it might be possible to have different versions of Pianteq living together, not that there's anything wrong with that, in your case, since you have mentioned your OS problems and I don't know enough about that specifically, In any case where weird problems exist with user data shared by programs, I would certainly recommend uninstalling one version and if that doesn't solve it, then also uninstall the other (reboot for the old "Have you turned it off and back on again" satisfaction) then pick one and only one version and install only that. The number of versions shall be one. And one shall be the number of versions. There shall be not three, nor two versions but only one version and that version shall be the only version etc..
I'd generally recommend the latest version - it's a similar size to older versions and has improved Linux latency in case you're not in Vista now, but already using *nix??
You might also want to check over Pianoteq's install log file before unininstalling your current version(s) and/or after a new install:
"install.log" is a smallish text file [found in the "documentation" sub-folder where you install Pianoteq] can be viewed in a plain text editor or notepad etc. to check out what happened during install. Some clues might be there. For example, at the end of the file you want to see something like this in Windows..
1066-11-09 14:18:25.894 Installation process succeeded.
1066-11-09 14:18:25.908 Need to restart Windows? No
1066-11-09 14:18:25.921 Deinitializing Setup.
If everything seems OK with that file after the big reinstall, then fingers crossed from there..
Sincerely hope that all helps you and others.
Some apologies for mystifying Kubric film references for fun.