I posted a reply to the main edition (similar problem) by mistake but maybe some comments will provide some ideas?
I am trying the 64-bit live cd but no issues - it logged in automatically at boot and I was able to switch to the Cinnamon session without issue. It shouldn't need a password. Just hit enter but that's not working for you?
I used Unetbootin to create my media on a usb drive. A Lexar Firefly, an older one but it's fast enough and been really good for using unetbootin and having my live distros (iso) on usb.
You might try re-burning the media or using a different source or program if the media integrity check is suspect.
P.S. Synaptic worked for me - 'didn't ask for password.