First check if the option 'Automatically run Notezilla when I log on to Windows' is enabled in Notezilla Preferences. If it is already enabled, then disable it, Press Ok so that the window closes, come back to Preferences screen and enable it again and press Ok.
To access Notezilla 's Preferences, right click on Notezilla icon and choose Preferences from the menu.
Also check the Startup list in Windows Task Manager. Make sure Notezilla is not disabled in this list.
Right click on the Windows taskbar and start Task Manager from the menu to see these options.