I have implemented a heating control system with a Pi running Domoticz home automation server, a few web pages and a control loop implemented as a python script. I'm running this system headless, and I have a problem the system hangs after a week (or so) flawless operation. The Apache webserver does not respond and I can't login remote with ssh (Putty). I have implemented a basic watchdog function that monitors the Domoticz process and the Python script. Beside this the watchdog function ichecks network connectivity by pinging my local router. The watchdog is implemented as a shell scrip executed as a cron job every 10th minute.
The thing is when the system stops responding, the watchdog still kicks in every 10th minute and everythings looks OK. The Domoticz and Python process is up and running, and I have have network connectivity. So the system seems to run quite OK, but I can't login nor open any web page. If I try to login with Putty, I can see the sequence when SSH is validating keys etc. but it looks like the system fails to start a shell session. Nothing happens after the init sequence. No prompt - nothing.
Does anyone have a clue what could be the reason behind this strange behaviour? I can't see anything strange in the log-files under /var/log.