Repeated error messages

[oldman]

I am getting repeated error messages that are making my Nexus 7 unusable.  Every time  I use it a "Couldn't sign in" (GMail) message appears.  I have changed my password and can sign in on my PC where I have no problems.
I have tried deleting GMail and every other google based app I can find but the error message is repeated ad nausium.
BTW the message pops up in every app its just stopped me using Facebook

[birdastrompgman]

Your gmail account email or password is corrupted.

Add a new Google account in >Settings >Accounts >Google, and delete the old account.  Then add the original account back.

Or do a factory data reset in >Settings >Backup & reset >Factory data reset.  Then set up your correct Google account during initial setup.