I have been struggling to figure out what the problem is with my iPhone 4 running JB iOS 4.0.1. I constantly lose connectivity, both on 3G and on WiFi, but in each case the phone has (and reports) full bars. In other words, it SHOULD have reception, but doesn't. Mail won't download and other apps report that "no network is available" or whatever the error is. Often, when I start the mail app, it will then connect and download all of my mail (Gmail using Exchange, and an actual Exchange account). Other times, it will just sit there trying to connect. I have re-imaged my device (and re-jailbroke) with no difference. I'm not really running that much on top of the JB -- biteSMS, intelliscreen, 3G unrestrictor (normally not turned on), SBSettings, WiFi Sync. Somehow Erica Utilities is also installed, it must be required by one of the foregoing. Any idea? Anyone else experiencing this?