darktable 3.8 flakey, where can I find the last 3.6 for windows?

I would uninstall darktable and reboot your PC.

I would then copy the AppData\Local\darktable folder to your Desktop, before returning to AppData\Local\darktable and deleting data.db and library.db

I would then copy data.db-pre-3.8.0 from the Desktop backup folder to AppData\Local\darktable then rename it data.db

I would then copy library.db-pre-3.8.0 from the Desktop backup folder to AppData\Local\darktable then rename it library.db

I would then install darktable 3.6.1 and say No to the question about keeping previous installation.