Loss of signal after reboot

Question

I am losing my iPhone's signal everytime it is rebooted, for example when it runs out of battery. Then, after boot up and after entering my PIN code, it keeps saying "no signal" and the only solution is to do a reset by pressing home+power buttons at same time.
Can this problem be solved?
P.S.: I've recently travelled to another country and used roaming.
         I've already done a reset to my network settings.
Thank you all!

Answer 1

Yes, alternate universe appears to be the most logical explanation. After months of no signal at all on the iMac, but great signal on the four other wireless connections, suddenly with no other changes or adjustments, simply doing a QuickTime update, causes the signal to re-appear during the update, to remain during multple reboots - even after rebooting in OS 9.2.2, and then rebooting again in OSX.4.6 the signal is still great - and even after five days the signal is still great - no signal fluctuating over the past five days (that had been a common phenomena before) - no signal drop offs during the past 5 days (that also had been a common phenomena). What? was it one of those wild coincidences, that at the precise moment that I was doing the QuickTime update, that actually an hideous, undetected RF Interference source chose that exact instant to stop interferring and to remain non-interferring until this present moment (doubtful) - or was it somehow related to software or to the update process? (I realize that this is not an attractive hypothesis, but is it remotely possible? - Of course, if it is in someway, that Apple wouldn't come out and say as much - not prudent -, but would attempt to correct it in a subsequent update)
---- So Gino, re-enter the real universe, don't speak these things, but be quiet and simply be satisfied that you have a good signal again - you'd be better off not even remembering that these other things even happened.