Next, have you done a battery pull... leave your device on, pull the battery, leave it out 20 seconds, put it back in, then wait for the device to boot up... give this a try then report back.
Sounds like everything I would have done if I had this issue... next I'd be calling T-Mobile... I assume you have a BB Data Plan and are receiving emails and internet connections through EDGE.
I also have this problem however when I try to load it it just says you must have a data plan....also my maps application will not work and various other 3rd party ones due to it says check bis/bes settings and you do not have a dataplan.
The thing is I do...I am with Vodafone...I get emails to the phone so can't understand it...