What exactly did you do to get this working I am having the same exact issue.
I have edited:
wp-content/plugins/w3-total-cache/ini/xcache.ini
xcache.admin.enable_auth = Off
Like stated in:
https://xcache.lighttpd.net/wiki/XcacheIni
Still getting the white pages, have checked every error log possible with nothing. The only cache I can clear is the disk cache not opcode.
Thanks!
