My guess based on what you stated in prior message. Without seeing the phone in person it's difficult to give proper diagnosis.
Other handsets can work with out issue so the fact your wife's phone works fine does not mean anything. Download speed fluctuates as well so not really a good identifier or troubleshooting piece in regards to your error.
Factory reset will usually cure things but is a last resort. I've not seen many people post with this issue so it could be geographical issue or a program on your phone and/or account setup issues.
Regardless, please post your results to the class :-)