gMail app on Hero no longer checking my gmail account...
You can check out "K9mail" on the market... The BEST I have seen so far. Since I am not familiar with the Gmail app, I can't give you too much advice other than try checking the settings of the app or maybe see if you have "Always-on mobile data" disabled... If this is turned off, your data will not work if the phone is locked. (This saves a LOT of battery if it is turned off though)
"Always-on mobile data" is turned on. I have K9 mail installed...but it is complaining about my gmail password being wrong...even though I can log into gmail via the web browser using the same password...just plain weird to me...
I ended up doing a factory reset on the phone and the gmail app started working again. I am still having an issue with K9 Mail and Mail Droid saying my password is incorrect. I know the password is correct since it is the same password I use in the gmail app.