Hi there,
after upgrading to 0.9.4 I have the same problem. The site is not working as soon the plugin is activated. Just like Tybaze I'm using Ubuntu 10.04.4.
Other versions:
Apache: 2.2.14
PHP: 5.3.2
WP: 3.8.2
W3TC: 0.9.4
There's nothing else in the logs, just a Segfault
[Wed Apr 09 09:39:51 2014] [notice] child pid 28026 exit signal Segmentation fault (11)
0.9.3 worked without any problem. The above mentioned fix does not work for me. :/