Kernel hang with latest snapshot

[David Boreham]

> Sorry, I didn't see your reply when I was sending this out. I will 
> take a look at iosyscall.open.entry, and will check the remaining 
> codes of potential invalid pointer access. Thanks.

I see crashes with every io syscall I've tried. It would take quite a 
while to
try every one (need to reboot every time). open, read, write, close for 
sure crash for me.