We are experiencing some intermittent problems with the web server architecture — applications sometimes stop responding at all and apache seems to become stuck — it also seems to affect the fastcgi module which renders all the non-php web applications unusable.
We have narrowed the problem to a potential culprit: APC, the PHP cache framework we are using in production. We have downgraded to version 3.0.1 and the problem seems to have gone away — but we remain vigilant.
We are carefully monitoring the web server for problems, do report any unexpected behavior 
