Fatal error for Classifieds 2.1.6

Hi,

I get the following message when trying to activate Classifieds latest version:

Plugin could not be activated because it triggered a fatal error.

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 5791625 bytes) in /var/www/ mydomain .com/public_html/wp-content/plugins/w3-total-cache/lib/W3/Cache/Apc.php on line 41

Any ideas? Besides - deactivating W3 site wide?

Cheers,

Johnny