If you want to keep your system safe from unwanted access then locking system is the best way. The default locking provided by windows takes you to the logon screen.
The logon screen takes you out of windows active screen and you cannot view activities going on your system. These activities may include a copy action, antivirus check, graphic rendering tasks etc.
Clear Lock is a freeware portable application that can lock windows active screen with a transparent layer. The main difference between this locking and the traditional windows locking is that it allows you to view all activities ongoing but you are not allowed to make any actions until unlocked .
Using Clear Lock is easy, the first time you execute this application you have to give a new password to be used.
Locking will be done automatically from the next time you click on the application.
This application is available for both 32 and 64 bit versions of Vista and Win 7. If you think that you have forgotten the password that you kept initially, just delete the .ini file that is created in the application folder. It will be automatically created the next time.