I tried uninstalling the FB app a few days ago too thinking maybe that was it, didn't matter, problem still persisted.
Mine does it all the time even if I have full 4G signal... I don't have the Facebook app. If I want service back fast I have to turn my phone off then back on, otherwise it has taken up to or more than 5 minutes.
DROID RAZR MAXXIMIZED!!!! PREPARE TO BE VANQUISHED!!!
FEEL THE POWER OF DROID!!!
I see a lot of mentions in this post about "bars" of 3G or 4G signal strength. It's my understanding that the bars measure phone signal strength only. Data signal strength (4G or 3G) is not shown on the taskbar.