Zen Cart v1.2.7 is grossly incompatible with MySQL5.
Basically, don't mix them.
If you need to mix them, upgrade your Zen Cart version to v1.3.7 or newer.
You say it's only appearing once. Consider yourself overly lucky.
(Actually, I'd be very concerned since that's inconsistent with normal operation.)
The thing is ... Zen Cart v1.2.7 SHOULD BE VERY AFRAID of MySQL 5.
The newer versions (1.3.8 to some extent, and even better in v2.0.0) do give clearer warnings of incompatibility, or a complete intentional halt where a known incompatibility exists.
Keep in mind ... Zen Cart v1.2.7 was built on architecture that existed before MySQL 5 was largely embraced. Thus, it was a little hard to write code to anticipate the incompatibilities. Much has been learned since then, and future versions will be much less painful to accommodate.
Keep in mind that Zen Cart v1.2.7 was released in February 2006, and there have been more than 8 new versions released since then, all with increasingly greater compatibility with PHP5 and MySQL 5.
You are VERY STRONGLY ADVISED to upgrade if you're using MySQL 5 or PHP5.
Sorry, I don't mean to rant ... just to be emphatic.





