how do you get your phone-email to stop erroring out?

I'm too lazy to check 5 mil responses... sorry... I have an imagio (and got the same error on my tuch pro 2 that I traded in for this one when setteling on this one) every time it tries to check my origonal email (gmail) it errors out even though I entered the coorect email account and password 15 times AND have deleted the settings and tried again 4 or 5 times. it keeps comming up with the same error. it also does it when I send/recive. none of my other email addresses have this problem. AND windows Mobile mail reads my gmail just fine... so how do I get it to stop erroring out?

it don't give me a error number or any thing it just says incoming e-mail password check user name and password and try again.  user name:{ } password { }
and save password[]

Ive deleted the account many times and entered the correct info over and over again. I've also removed the battery many times...I've recived the same responce on two diffrent HTC devices