I would suggest that instead of screensaver locks, everyone has their own user account. At my work place we have two computers for 12 teachers to share. Each of has our own user account set by name and employee number to start (after the initial log in... we can change our username and password for future log in's). Any information we enter into the agency system (i.e. student files) is time stamped along with our name. We must also be logged in to our own user account to access our work email. When we're done with the computer, we of course have to log out. This method is a safegaurd for the agency. If there are errors in the agency files... administration can tell who made the mistake, and contact them to correct it, which is handy for an agency that has teachers spreading over numerous cities, but yet need to be connected to the same agency network.