I can't explain it but I think it coincided with "Windows Update." Sometimes I'd rather watch "Weekend Update".
You can uninstall and re-install Classic Shell so you're sure to have the latest.
Bob
Why does my shell menu icon disappear in the bottom left of my tray and then is replaced by the windows8 menu icon - I click on it and cant get to shell but am taken to the windows 8 screen?
The point of me getting shell was so I would not have to go to the w8 screen all the time.

Chowhound
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