K750i reboots itself PLEASE HELP !!!

[lucja]

What do you mean by "check your SIM card"? I tried hundreds of times to remove and reseat a handful of diferent SIM cards. All the same. If I don't insert any SIM the phone won't reboot but instead asks for a SIM. It is strange because it started to reboot even with the T-Mobile SIM that it used not to reboot but now started to reboot with that SIM too. I took the phone in an area with no GSM signal and phone still reboots. It is wierd. I'm thinking to reflash the phone with the oldest firmware.. see what happens. Any idea is welcomed.

PROBLEM FIXED. Finally I got to the bottom of this.. (or that I think). I reflashed (again ) the phone with the oldest firmware available on TOPSONY.com which is R1AA008 and the phone won't reboot any more. So it was not a SIM problem or a hardware problem. It is weird anyway. I've noticed another problem though, I have only 3 bars of signals compared with the other 2 k750i's that I own on the same network which have 5 bars. It still may be a power amplifier problem...


UPDATE: After 6 months of heavy use of the SE K750i with the reboot problem it still works strong . No problem since I reflashed with the oldest firmware (which is RAA008). There was no hardware problem. I still can't figure why the phone reboots with all other firmwares. I'm afraid to reflash with a newer FW because I think I will end up with the reboot problem again.
Weird isn't it?
I have only one explanation: the size of FW RAA008 is smaller than all other newer firmwares. I might have a phone with some damaged clusters of internal memory. A large firmware will try to use this part of memory which is damaged while a smaller FW doesn't need to. With a larger FW size the phone will try to access this damaged areas, was unsuccessful and was forced to reboot.
Any ideas?