Okay guys !!
Thank you very very much - you have been very helpfull and threfore i'll try to ask another thing with unlocking:

when a user press CTRL,ALT,DEL and locks he's account the msg on the screen says:
"the computer was locked by XXX and it can only be unlocked be user XXX or an adminisrator"

my question:
can it be unlocked by another user (not an admin) ? and how do i give someone the premissons to unlock a workstation ?

Thanks a lot !

Ron