This behavior is the result of a bad firmware update that has been released to the public. Please see the many threads that have been started over this issue over the last month.
Firmware version 3A will require you to obtain a new device under the VZW warranty. If you get a 7730 as a replacement then disable automatic updates until the next patch is available.
Even if you are outside of warranty its worth it to call in your problem. You need a replacement device to resolve this issue. You cannot roll back firmware on a Jetpack.