If you’re getting this problem,it’s Google’s Fault, and not the Windows 7 / Windows 8 Phone’s.
Go to the following URL, put your password in and enter the captcha. This will solve the problem and let you use your Gmail account on your Windows Phone.
https://www.google.com/accounts/DisplayUnlockCaptcha
It seems to disable some captcha security setting on your Gmail Account. Use at your own risk, I don’t know what else it does.