PHP error

Hi,

One of the editors on my site recently told me he saw this error while refreshing the home page:

Fatal error: Out of memory (allocated 12058624) (tried to allocate 19456 bytes) in /home/mydir/public_html/mydir/sites/all/modules/members/members.module on line953

I found this in the logs, with his user name:

Type php
Date Thursday, August 7, 2008 - 12:33pm
User hisusername
Location http://www.example.com/
Referrer http://www.example.com/
Message mysql_query() [function.mysql-query]: Unable to save result set in/home/mydir/public_html/mydir/includes/database.mysql.inc on line 147.
Severity error
Hostname his host name

Can anyone point me in the right direction?

We are running a little low on memory for the amount of traffic we have, but I have not seen this before.

Thanks,

Aaron