Bitcoin-Qt 0.8.1 silent crash during mining

[Searinox]

I had work today so I left at 8am and came back at 6:50pm. When I came back I noticed the GPU tray temperature indicator was very low so I immediately knew something was wrong. P2Pool was reporting a loss of connection to the Bitcoin server. And indeed, my Bitcoin-Qt had mysteriously closed, halting all future mining. I've been mining for 10 days now and I haven't had this kind of issue. This is the first. If Bitcoin is this unstable I might in the future waste more valuable mining hours thanks to the client crashing. Where can I look up logs for what went wrong and what can I do to avoid this repeating?