If I use the network (an atheros card on a WPA netowork) for anything siginificant the machine locks up as per the trace below. Interestingly, it doesn't seem to have a problem with aquiring an address via DHCP.


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Unread portion of the kernel message buffer:


Fatal trap 12: page fault while in kernel mode
cpuid = 2; apic id = 02
fault virtual address	= 0x0
fault code		= supervisor read data, page not present
instruction pointer	= 0x8:0xffffffff8025e2f2
stack pointer	        = 0x10:0xffffffffaec9e630
frame pointer	        = 0x10:0xffffff00018fa100
code segment		= base rx0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 16516 (fetch)
trap number		= 12
panic: page fault
cpuid = 2
Uptime: 2m56s
Physical memory: 2034 MB
Dumping 251 MB: (CTRL-C to abort)  236 220 (CTRL-C to abort)  204 188 172 156 140 124 108 92 76 60 (CTRL-C to abort)  44 28 12

Reading symbols from /boot/kernel/snd_ich.ko...Reading symbols from /boot/kernel/snd_ich.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/snd_ich.ko
Reading symbols from /boot/kernel/sound.ko...Reading symbols from /boot/kernel/sound.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/sound.ko
Reading symbols from /boot/kernel/aio.ko...Reading symbols from /boot/kernel/aio.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/aio.ko
Reading symbols from /boot/kernel/linux.ko...Reading symbols from /boot/kernel/linux.ko.symbols...done.
done.
Loaded symbols for /boot/kernel/linux.ko
#0  doadump () at pcpu.h:194
194	pcpu.h: No such file or directory.
	in pcpu.h
(kgdb) where
#0  doadump () at pcpu.h:194
#1  0x0000000000000004 in ?? ()
#2  0xffffffff804964a9 in boot (howto=260)
    at /usr/src/sys/kern/kern_shutdown.c:418
#3  0xffffffff804968ad in panic (fmt=0x104 <Address 0x104 out of bounds>)
    at /usr/src/sys/kern/kern_shutdown.c:572
#4  0xffffffff8075ff74 in trap_fatal (frame=0xffffff00044d66a0, 
    eva=18446742974267905128) at /usr/src/sys/amd64/amd64/trap.c:724
#5  0xffffffff80760345 in trap_pfault (frame=0xffffffffaec9e580, usermode=0)
    at /usr/src/sys/amd64/amd64/trap.c:641
#6  0xffffffff80760c88 in trap (frame=0xffffffffaec9e580)
    at /usr/src/sys/amd64/amd64/trap.c:410
#7  0xffffffff8074664e in calltrap ()
    at /usr/src/sys/amd64/amd64/exception.S:169
#8  0xffffffff8025e2f2 in ath_start (ifp=0xffffff00011cd800)
    at /usr/src/sys/dev/ath/if_ath.c:1747
#9  0xffffffff8052fab6 in ether_output_frame (ifp=0xffffff00011cd800, 
    m=0xffffff000421eb00) at /usr/src/sys/net/if_ethersubr.c:405
#10 0xffffffff805300e2 in ether_output (ifp=0xffffff00011cd800, 
    m=0xffffff000421eb00, dst=Variable "dst" is not available.
) at /usr/src/sys/net/if_ethersubr.c:374
#11 0xffffffff805755df in ip_output (m=0xffffff000421eb00, opt=Variable "opt" is not available.
)
    at /usr/src/sys/netinet/ip_output.c:551
#12 0xffffffff805ce48c in tcp_output (tp=0xffffff0004216b60)
    at /usr/src/sys/netinet/tcp_output.c:1135
#13 0xffffffff805d880d in tcp_usr_rcvd (so=Variable "so" is not available.
)
    at /usr/src/sys/netinet/tcp_usrreq.c:738
#14 0xffffffff804ef5cf in soreceive_generic (so=0xffffff001040c570, psa=0x0, 
    uio=0xffffffffaec9eb00, mp0=Variable "mp0" is not available.
) at /usr/src/sys/kern/uipc_socket.c:1825
#15 0xffffffff804cee1d in dofileread (td=0xffffff00044d66a0, fd=3, 
    fp=0xffffff00047e4168, auio=0xffffffffaec9eb00, offset=Variable "offset" is not available.
) at file.h:242
#16 0xffffffff804cf18e in kern_readv (td=0xffffff00044d66a0, fd=3, 
    auio=0xffffffffaec9eb00) at /usr/src/sys/kern/sys_generic.c:192
#17 0xffffffff804cf27c in read (td=0xffffffff80e62000, uap=0xffffff00044d66a0)
    at /usr/src/sys/kern/sys_generic.c:108
#18 0xffffffff807605c7 in syscall (frame=0xffffffffaec9ec70)
    at /usr/src/sys/amd64/amd64/trap.c:852
#19 0xffffffff8074685b in Xfast_syscall ()
    at /usr/src/sys/amd64/amd64/exception.S:290
#20 0x0000000800c0297c in ?? ()
Previous frame inner to this frame (corrupt stack?)

Fix: 

Going to roll back to my old kernel I think.
How-To-Repeat: Boot PC, fetch someting large or open firefox, go myspace or any other website really (although the really simple firefox start page is usually okay).