Help me find out why my machine stopped mining during the night

[CYPER]

So I just started mining using:
4x XFX 5870 @ 960Mhz Core = 434 Mhash/s = 70 degrees maximum temp.
Gigabyte GA-770T-D3L, AMD 770, AM3
AMD Athlon II X2 250
Ubuntu 11.04 32bit
SDK 2.1
Latest Phoenix using phatk kernel

I left the machine mining at 5am and went to bed.
When I woke up it wasn't mining so I tried to connect unsuccessfully using VNC. I then connected using SSH successfully and did sudo reboot.
I checked the logs after the reboot they indicated that it stopped 2 hours earlier.

Here are the kern.log and syslog

Is this normal?

Jul  1 09:40:32 Woody kernel: [17160.748408] INFO: task phoenix.py:3170 blocked for more than 120 seconds.

If you need any other logs please ask.

How can I find out why it stopped mining?

[phorensic]

I did some research and I see other people have this error, but with different programs obviously.  They all point back to the kernel.  Try upgrading your kernel.  They also mentioned video card drivers, which directly communicate with the kernel, so just make sure you are up to date on those also.

[Xenomorph]

I have a horrifically-bad Internet provider, and during any one of the (many) daily reboots of my modem (due to communication errors), one of my miners will usually stop when disconnected.

So a "less than perfect" network connection can cause a miner to quit.

[BiggieJohn]

use phoenix rising or something that can check/restart miners. 
it's P2P network, yeah , drops happen