Fatal error allowed memory size .... mysql

When I try to go into the Sales>Mail setting in Admin I get the error: "
Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 630 bytes) in /home/<my username>/public_html/system/database/mysql.php on line 29"

Searching around says either it's an image problem (my problem seems to be with the database) or I need to up my memory in php.ini but mine is already set to 64M. What else could be the problem, should I check?

Thanks

I think it all depends on what kind of server your on, in my experience just changing the memory size in the php.ini file wont do, because there is a global php.ini for the whole server.

Best bet is to run a php.info file on your server.

<?php

phpinfo();

?>

then check your memory size, if its too small, contact your host.

Ok I ran that but I'm not sure what I should check, my memory_limit for both local and master level are set at 64M, is that what I'm looking for or something else?

Edit: I guess another question could be, is there something else hogging all my memory? I've only got wordpress installed besides opencart, but before that I went through zen-cart, joomla/virtuemart, magento to give them all a test, would that impact anything?

Thanks

So I changed the php.ini memory_limit to 128M and now I get the error message: "Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 5567405 bytes) in /home/<username>/public_html/system/library/cache.php on line 43"

Does that help narrow down the problem?

Edit: I'm using Opencart 1.4.9.1, I keep forgetting to add that.

Now I'm updated to 1.3.9.3 and upped the memory to 156M, I got a new error message: "Warning: fread() [function.fread]: Length parameter must be greater than 0 in /home/<username>/public_html/system/library/cache.php on line 31
Fatal error: Allowed memory size of 163577856 bytes exhausted (tried to allocate 12809956 bytes) in /home/<username>/public_html/system/library/cache.php on line 48"

Wait upping it to 256M let it work, turns out that's not what I'm even trying to do, ha.

Hello guys...I am having the same problem and same error:
PHP Fatal error: Allowed memory size of 50331648 bytes exhausted (tried to allocate 71 bytes) in /home/tentatii/public_html/system/database/mysql.php on line 30

I called the hosting support and they told me that my maximum memory for PHP is 48 Mb. I did not modify anything to my website during the last month but since yesterday, my website is not running because of this memory limit.

Is there any way to minimize the memory usage of my website? Or do I really have to buy from hosting another hosting package to have more memory? I want to mention that my website was working fine so far...

Thank you!