Fatal error: Allowed memory size

Hi

Thank you for your excellent plugin.

I have just been given this message when trying to reactivate the Crayon Syntax Highlighter;

Plugin could not be activated because it triggered a fatal error.
Fatal error: Allowed memory size of 402653184 bytes exhausted (tried to allocate 64 bytes) in /www/wp-includes/wp-db.php on line 2416

I checked with the web host who said we have plenty of memory.