Limit Usage of pc

i'd like to make a code, where i can limit pc usage so that a user can only log on to the computer for a certain time i thought of using a timer but it would be restarted if the user logged on again. I am only a beginner with vb can anyone give me an idea of how to do this.

Thanks in advance
chris1990

you could save the settings so that even if the user logs out it will save how long they were on so next time they login it will know..

savesetting(app.name, user, "TimeLog", timeon)

don't forget to load it

timeon = getsetting(app.name, user, "TimeLog", 0)