Windows 7 - Password Change / Remove Password Problem

I've created a password for the guest account. Now I can neither change nor remove it.

Logging on as admin I can't find a setting to change or remove guest account's password.

Logging on as guest I am getting the "windows cannot change password" warning if I try to change or remove it.

On guest account using ctrl+alt+del>"change password", now I get a "access is denied" warning.

Any kind of help would be appreciated. Thanks.

PS: The whole issue has started with me seeing a warning on Bitdefender's Vulnerability module telling that the guest account has no password. I clicked on it and created a password for my guest account from within BD. That doesn't necessarily have to be related with the problem, just FYI.

uninstall bitdefender first, then reboot, next go to control panel, User Accounts and Family safety, User Accounts, select change your windows passwords and remove password from guest account and any other accounts you wish. Then reboot.

"uninstall bitdefender first, then reboot, next go to control panel, User Accounts and Family safety, User Accounts, select change your windows passwords and remove password from guest account and any other accounts you wish. Then reboot."

Thanks for the reply.

Are you sure that it's Bitdefender? Even if I would do what you described I have to install Bitdefender again...

No I'm not sure it's Bitdefender, you stated that it started w/a warning from that app. This is what got me to thinking it might be the culprit and corrupted your password/login accounts. It's just an educated guess. Yes, you would have to reinstall it again. It too could be any number of things like spyware, malware, adware or a virus or your registry is corrupted or a combonation of them. Lets start with Bitdefender first and then we can go from there and systematically rule stuff out one by one.