when i start windows it wont get through the session start screen, i have never used an account, it shows the account "user", when i open it it starts session and automatically ends it, returning to the same screen. is this a virus? what can i do?

boot into safe mode, open under administrator,
open user accounts, change to 'welcome' screen only

already done that, but in the admin account it asks for a password, which i dont have, i dont remember really if i ever put one, so...

remembered the password, it happened the same thing