Yesterday we were at a client site trying to fix an email account that wasn't syncing up with outlook. It kept saying the password was wrong or there was a connection error. However we could log in through the web portal no problem. What happened was google had locked the account as being suspicious. Below are the links to where you will need to go to unlock them.
This is just a tip if you ever come across an issue syncing gmail to outlook or similar product. For a user with google apps:
https://www.google.com/a/CompanyURL.com/UnlockCaptcha (replace CompanyUrl.com with the real company url)
Or if it is a plain gmail account:
Type in the username that is having the issue and submit password. This will unlock the problem account. Gmail has this as a security measure for accounts that seem to either be accessing email too often or it deems to have been hacked into..