Back when I used to use Windows 98 and then XP primarily, the phenomenon of having to reboot when carrying out a minor system change or installing an inconsequential update caused much exasperation, something which was far less of a problem on Ubuntu.
Then I moved to the Mac and was again disturbed by the occasional mysterious requirement to restart the machine merely because the web browser or worse, iTunes (which I do not even use) had updated itself.
And then I got a Windows Vista box and was reminded of the good old days:
Nice. I've never used Windows Mail, but now it wants to reboot the computer just because it's updating its own files? Piss awf!