In Vista (unlike Windows XP), Fast User Switching works if you’re on a network domain. To turn off Fast User Switching, choose Start, type gpedit.msc in the Search box, and then press Enter. (If a security prompt appears, type an administrator password or confirm the action.) In the Group Policy Object Editor, choose
Local Computer Policy > Computer Configuration > Administrative Templates > System > Logon > enable Hide Entry Points for Fast User Switching > OK.
To find out who else is logged on to your computer: 1. Right-click an empty area of the taskbar and choose Task Manager. or Press Ctrl+Shift+Esc. 2. Click the Users tab to view users and their status