Share your experience!
My Arc S has gone into an infinite autoreboot mode. I tried downgrading to 2.3 to see if it was an issue with the ICS. But the problem persisted. One amusing observation after playing with my phone was that it works absolutely fine when there is NO SIM inside! I am taking it to a service centre. Hope there is a solution! Sony Mavericks please help !!! 
Hard to tell what might be the cause since you've tried a bunch of stuff to sort it out.
If an update and/or repair didn't sort it out I'd recommend you to hand your phone in for a check and/or fix.
The best way to proceed in that case is by contacting your local Sony Mobile support. You can find contact info on the link below.
Thankyou Peter. Can you atleast suggest if it is a bug or an issue with the hardware circuit?