As I am sure many of you have noticed 3G data is down on your Thunderbolts. As I have discovered from some talks with Verizon techs the reason for this is that Verizon's eHPRD 3G network is down right now. This is the specialized 3G network used only on the Thunderbolt and supports voice and data at the same time and faster 3G/4G switching. Until this is fixed you can manually fix this by dialing ##778# and hitting send in your dialer. Password is 000000. This will take you to your programming screen. Go to modem settings and then Rev A, change it to enabled and then hit the menu button on your phone and commit the changes. It will tell you to reboot and the problem will be fixed as you will now use the standard Rev A 3G networked used on all other Verizon 3G devices and of course if you have 4G it will use that if its available.
There is no need to do a hard reset. Basically when you first set up the phone it automatically provisions this setting based on whether or not eHPRD is available in your area which is why when you hard reset it fixes the problem for people as the phone will then automatically change this setting to Rev A enabled since eHPRD is down.
Obviously once Verizon fixes this issue you will want to change this setting back unless of course Verizon is able to push this change out to all of the phones when the problem is fixed.