Data Network mode doesn't get activated on gingerbread 2.3.4 This happened all of a sudden. I could not start the 3g on my phone.

The Data Network mode is always deactivated now.

Although, when I go to Settings > Wireless and network settings > Mobile network settings,
the Use packet data option is checked.

Unchecking this option and checking again doesn't work.

Installing the internet settings again from the service provider also didn't help.

Restarting the phone didn't help.

Restoring factory settings didn't help.

Any idea what's going wrong?
Do not know if you got it sorted but I had the same problem and did this:


Tap Settings > Wireless and Networks > Mobile networks > Access Point Names 
Then tap on one of the relevant APN's pertaining to your provider, such as, for example O2 Mobile Web (Pre-pay or contract) 
Set the APN Type to 'internet,mms' 
Tap on Menu, tap on 'Save'.


Back out of the Access Point Names screen, back out to Mobile networks, then:


Tap on Packet data (In some ROMs this could be labeled as Data Enabled), and also, Data roaming to turn them off.
Turn those two options back on 


And voila its working again!