if you go into the control panel and go to users what does it say in there? unfortuinately it sounds like it was set up wrong when installed this may be fixable just le tme know what it says...
try from safe mode
a lot of times OEMs will create an admin account with out a password
if it requires a password try
administrator
password
if that still does not work DL this tool to reset the administrator account password... NOTE do not create a password, just make it blank or no password for the time being http://home.eunet.no/pnordahl/ntpasswd/