Windows-button commands aren't handled by explorer.exe, which is where the taskbar, start menu, folder windows, and other shell crap is run from.
I'm pretty sure Ctrl-Alt-Del (Windows Security), Ctrl-Shift-Esc (Task Manager), Win-R (Run), Win-L (Lock), and most of the rest of those sort of commands are all run by System, which is basically a fancy way of saying "the fricking WinNT kernel." That's also why you can't change them.
If explorer.exe crashes, just run another instance. It's just a damn shell. Hell, replace it if you want.
Just because it's not Linux doesn't mean it isn't properly designed in at least some ways.