MarketPress error when activating

Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 94 bytes) in /home1/johnnym2/public_html/xxxxx/wp-includes/capabilities.php on line 494

I get this error on a child blog of WPMU but not on others.

I think it could be a plugin conflict...?

I will try to disable them all and reenable the plugins 1 by 1...