Password Problem After Migration

The internal hard drive on my old iMac seems to have crashed, as I get a folder with a question mark each time I start it up now (except for once, and I was able to log in normally). I decided to get an external drive to replace it, as I am not able to take apart the iMac and replace the drive internally.

After searching these forums for help, I rebooted using the option key, and reinstalled Snow Leopard on the external hard drive. After the install, I was asked if I wanted to restore from a Time Machine backup. I chose this option, and after many hours the migration appeared complete.

However, once I tried to sign into my user account, my password was refused. I am 100% certain about my password, and my password hint confirmed that, as well as my written log. I also tried to log into my wife's account, again without luck.

Is there someway my password has changed without my authorization? What can I do to get my iMac back to normal? Thanks in advance for your assistance.