When you logon to your user account, the Frequently Used Programs list in the Start menu may get reset with the factory default listing.
This happens if the StartMenuInit registry value is not set correctly in the registry. During the first logon to a user account, Windows is supposed to set the StartMenuInit value automatically. If that procedure fails for some reason, then Windows resets the Frequent Used programs list with the factory default programs list automatically at every logon, and pops up the Start menu automatically.
HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Explorer \ Advanced