If it's running unattended I believe you  What about CGminer uptime? I find it VERY sensitive to the pool connection ..
When the main pool connection is not active it automatically switches to the second pool .. but if you have only one pool set up the hash-rate shuts down and/or cgminer restarts.
I had the SP30 several times mining PPC (LOL) because of some DNS issues, not under my control. Local p2pool nodes at the datacenter can definitely help in this regard.