I woke up this morning to find my son playing with my HTC Magic (running Android 1.6, aka, Cupcake). That's usually a non-event, except for today where he's tried a few too many times to unlock the phone using the pattern sequence.
After too many pattern attempts you're greeted with a form prompting for your Gmail email address and password in order to unlock the phone.
No problems! I enter said credentials, hit enter, and... Bzzzt. Incorrect email/password. I try it again, but still no cigar.
So I jump on my Mac and hit Gmail with what I thought was my email and password and voila it let's me in. Great, I now have a phone that I can't unlock. Long story short, I'm not the only one with this problem, and there's a fair few suggestions (including doing a factory reset) to overcome this bug.
As a last ditch effort, before I go down the factory reset path, I found one solution which was to use the word "null" as the password along with your Gmail address as the username, pretty sceptical of it myself but no harm in trying.
It actually worked.