I was browsing this forum on my NL920 using the default IE10 browser. About 30 minutes into it, the phone completely froze. I had to soft reset causing my date and time to reset as well. Really annoying.
It's probably just a general protection fault of some type. It sounds pretty normal. Report the bug and it will eventually get fixed. I doubt that it is hardware related, although if you are watching videos or doing other things that put the phone under a high load it could eventually overheat. Most phones aren't made out of the best materials for radiating heat, and over time could warm up to the point where the system will shut itself down to prevent thermal/heat damage.
I wasn't doing anything other than browsing. The phone wasn't hot at all before the freeze. It was during the freeze that the phone became really warm! I suspect it is discharging very quickly while frozen.
Looks like there are still show stopping bugs with the update.
Working in software and computers there is no such thing as random. The chances are the problem was with IE and a web page you were visiting. IE on my work PC is an absolute nightmare and routinely stops working. A lot of the time accessing this site for example.
never had that before
myself a power surfer, do have some lagging when a lot of heavy tabs, once or twice, other than that the S4 seems to be as smooth as a i7 laptop, in an equivalent sense of course.