Hi nappaji,
This sounds like a Windows problem, where either a screensaver with a password has been implemented (Control Panel - Display - Screensaver - Password Protected checked) or the person is doing a cntl-alt-del then Lock Workstation).
The administrator of the pc can also unlock the machine.
I would guess that there would be a Windows Forum with tec-tips, perhaps they can help further......
Kind Regards
Queenie.