wifi problem PLEASE HELP!!!

I have a blackberry 8520 with T-Mobile, OS version 5.0.0.900, no Blackberry plan. When I restart the phone, apps that claim to work over wifi can access data through my home network. Even BB App World works. However, after a short while, no app except the browser can access data over wifi. Strangely enough, the same thing happens if I'm subscribed to T-Mobile's web plan. Apps that claim to be able to work over a standard edge connection and not BIS still can't access data. I can always restart the phone via a battery pull or alt+shift+del seems to get the apps working, but restarting takes a long while and wastes almost 20% battery

BTW, the router I connect to is set to not broadcast the network name, and connecting to it requires the SSID in addition to the WPA key.

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