Wonder if you guys with 4.5.0.69 has the same issue?

I have 8320 from TMO with 4.5.0.69. The data link with EDGE or WiFi hasn't been very stable. For instance Gmail could work for a few minutes or an hour, but then for the next couple hours no new emails show up even if my account does have new ones. Then the next hour it might work again. The same thing happens for Google Maps and browser. All these while the EDGE or UMA logo is shown.

Is there anything I can do to improve it?