Site down - Can't create/write to file '/tmp/#sql_5351_0.MYI' error

Hi,

I have a site that was working just fine for over a month, and now all of the sudden, none of the products are clickable and I'm getting the error on the front page of the store :

1 Can't create/write to file '/tmp/#sql_5351_0.MYI' (Errcode: 13)
in:
[select banners_id, banners_title, banners_image, banners_html_text, banners_open_new_windows, banners_url from banners where status = 1 and ( banners_group = 'SideBox-Banners') order by rand()]

Can anyone give me a hint or idea as to what may be wrong - how to troubleshoot? I'm using version Zen Cart 1.3.8a

Thanks.

OK I found the problem but that leads to another question -

Does Zen Cart require write and execute permissions on the /tmp directory? I'm talking about the temp directory off root - /

nadsab:

OK I found the problem but that leads to another question -

Does Zen Cart require write and execute permissions on the /tmp directory? I'm talking about the temp directory off root - /

Zen Cart itself does not require it.
MySQL may require it, but that's a database and server config issue, not a Zen Cart issue.