Comment # 2 on bug 955352 from Wolfgang Bauer

You can disable the updater in the "System Tray Settings".

Still, it shouldn't notify you more than once a day by default. (though the
check time is nowhere saved, so it will check once on every login)

Do you maybe have another updater installed as well, apper e.g.?
If yes, does it help if you uninstall it?