Help please - Toshiba fingerprint scanner & password

Hello there,

I own a Toshiba Satellite P500 and have recently registered my fingerprints for scanning. Since doing so, when I go to log on it now promts me for a fingerprint, or requires a password. I have tried leaving the password blank to log on, but it says it is incorrect. I only run an admin account, and before registering my fingerprints, it required no password to access it. So these are my questions three. Firstly, if I removed the prints, will it restore the account to passwordlessness? Also, I have gone into the control panel in the past & have tried to add a password to my account, however it asked me what my 'old' password was before changing. I have tried leaving it blank, but it just screams at me that it is incorrect. So how may I also apply a password to my account otherwise? I know I must sound like a nitwit. I am running win7 btw. And... actually, only realised I have two questions. Please help. I want to avoid having to reformat in the event the scanner decides not to work, and I'd like to have a password on my account for security.