I recently jb'd my phone using blackra1n. I installed cydia and the main apps like boss paper, winterboard, themes, etc. Nothing out of the ordinary except the sinfuliphone tether hack. Everything works great except when I leave my phone idle for a while and try getting mail or going online, I get a message that it is unable to access the cellular network. I can get it working after I turn airplane mode on and off. Prior to my jb, this was never an issue. Has anyone else experienced this and if so, what should I do to fix the problem?