NetPositive cause unkillable thread and make shutdown impossible

[X512]

This is hrev53937.

Steps to reproduce:

1. Open NetPositive.
2. Drop /boot/system/documentation/BeBook/index.html that is located in be_book package on NetPositive window.
3. One of NetPositive threads will cause 100% CPU core load in kernel space.
4. After attempt to kill NetPositive, thread move to "Gone teams...".
5. It attempt to shutdown system, it will lock on "Clean up a bit".

100% reproducible on my environment.

[X512]

Backtrace of NetPositive thread that cause problem.

[X512]

previous_syslog contains a lot of repeating records like this:

vm_soft_fault: va 0x185d0000 not covered by area in address space
vm_page_fault: vm_soft_fault returned error 'Bad address' on fault at 0x185d0000, ip 0x8013e02b, write 0, user 0, thread 0x43a9

[waddlesplash]

Very strange, do we have some sort of infinite loop in the fault handler?

[cocobean]

X512: Be Book uses PNG images which may trigger the NetPositive issue.