Hi everyone,
I have the same problem from the beginning (3 months now). I can add a few details:
i have nothing wrong with wi-fi*: even when 3g doesn't work, i can still connect to wifi
when 3g doesn't work, after i try using an app requiring it, the battery drains very quickly (the whole battery in 4-5 hours maybe). so if i don't want to reboot directly, i switch to plane mode, and when i quit this mode, the name of my operator does not appear, it is clear i cannot receive or send any phone call or sms.

and doing this doesn't change anything for me*:
/sbin/initctl restart xsession/icd2
Does it really work for everyone but me ?

this is really a major problem. a smartphone without the internet is rather useless.

Thanks for your help in any case