I keep getting the same error message

[Frank]

Fatal error: Allowed memory size of 16777216 bytes exhausted at (null):0 (tried to allocate 262144 bytes) in /home/www/serotta/forum/includes/functions_search.php on line 251

[Frank]

I had to put in a title and one word in the text, then hit submit reply. After that posted, I had to go in and edit the text and add the details and hit submit reply. I then had to add the pics and hit submit reply.