When I choose Start/Settings/Control Panel/User Accounts, I get blank screen with an error message "Wrong number of arguments or invalid property assignment". When I go through mmc and try to add snap-in local users and groups, I get the message "Unable to access the computer. The error was: Invalid syntax"

Lieta: try this; when booting up to the Welcome Screen; set up a new Administrator account and call it "Change Control". see if this new account will allow access to the other user accounts. if still no joy, try this registry fix from Kelly Theriot: http://www.kellys-korner-xp.com/regs_edits/userinitrestore.reg make sure your Secondary Logon service is running; click Start, Run, type: services.msc scroll down to Secondary Logan and right-click it, select Properties, set to Automatic in the Startup type drop-down box. it may also help to do the same for Security Accounts Manager and for Remote Procedure Call. let us know what worked for you...