I have an OptiPlex 3011 and I'm getting a password error since I forgot the password. I've tried restoring windows nothing lets me Past the dell security manager box It says Please type the system or Administrator password which I know neither. Dell will not help any suggestions
You will need to look into this closely and try dell forced password reset long as you can prove ownership by receipt.
Also look towards the bottom, that might be the way to do it, but beware dell passwords are notorious for being not reset over the years. http://en.community.dell.com/support-forums/desktop/f/3514/t/19607691