IPhone 4 Full Reset

Hi,

I have on old IPhone 4 that I would like to give to someone as they don't have a smart phone.

My problem is, that every time I try to 'Erase all content and settings' I get as far as the Password Required page and when I try I always get the following message;

"VERIFICATION FAILED

The certificate for this server is invalid. Yuo might be connected to a server that is pretending to be "setup.icloud.com" which could put your confidential information at risk."

and offers me the options of 'Cancel' or 'RETRY'.

Then it just takes me back to the settings screen to start over.

Any help much appreciated.

TIA