We covered USB Safeguard which allows to protect files in USB drive with password, if you are looking to lock your opened apps and Computer with USB Flash Drive then you can use Predator. USB Desktop Lock is even better app than Predator allows to lock your Computer with your USB flash drive. You can use same flash drive to unlock your Computer also.
Related USB Drive Problems and Solutions Guide [PDF]
USB Desktop Lock with simple user interface without need of password uses your USB Flash drive as key to lock and unlock your Computer.
Install USB Desktop Lock into your Computer, plug your pen drive and select your Flash Drive by clicking “Browse for Flash Drive”. After that click “ Debug Validation Verificator “ . From then on you can use your Pen drive to unlock your Computer. User only need once to configure this .
When your PC is locked all opened windows and tabs are hidden, to unlock you need to plug in USB drive.Pulling pen drive out will lock your PC.
Be careful with these sort of programs if you configured this app to use your Pen drive as key, if you lost your pen drive then its virtually impossible to unlock your Computer.
USB Desktop Lock is freeware and requires .Net Framework 3.0 to be installed to work.