Since we all used to have laptops, the company had asked us to install a new software, Credant mobile guardian, for encrypting data on the hard disk. After installing it, the restart dialog kept coming as many times as it was rebooted. Finally, frustrated, I renamed the file name in c:\Windows\System32\CmgShieldUI.exe to CmgShieldUI_.exe and CmgShieldSvc.exe to CmgShieldSvc_.exe
Then, kill CmgShieldUI.exe from task manager (For n00bs out there, 'kill' means 'End process').
Hover over the tray icon & it disappears!
Also it might be a good idea to remove these from startup (msconfig).