Has anyone ever figured out how these Randomly-changed-your-settings-for-no-reason errors actually happen in the first place?
Because this has been a common problem with Windows computers as far back as I can remember: your computer behaves perfectly normally for years and then suddenly does something inexplicable; your home page has changed, your screen resolution is one setting higher or lower, your browser settings have changed, programs that used to load on startup suddenly don't, programs that never loaded before suddenly do, and default settings you've taken for granted for fourteen months suddenly change in a subtle way and now you have to go and change them all back.
My boss calls this "the perverse behavior of inanimate objects" but it appears to be purely a windows thing (although I have noticed this happening a lot with the latest version of Safari too). WHY THE HELL DOES THIS HAPPEN?
The vast vast majority of the time it is the end user who does something to change the settings and either does not realize they did or forgets. The settings on my windows systems never change all by themselves. Many of the settings you mentioned can be changed by other programs that are installed on your system. So when something goes wrong, got to the most basics trouble shooting 101 and try to remember any changes you made or programs that were installed in the last several days and go from there.