After about a week of problems with my wireless web, (always an unknown error) I was about to cancel service and return the phone -_-

fortunetely the CS I just talked with had a hotfix ready and waiting, and it's so simple I should've tried it already - a hard reset (press and hold the wireless button while reseting)

It started provisioning my phone as soon as I turned wireless mode back on!

Hope it works for you, although I'm sure it's not a univsersal fix =D