if you are using an older version of the software I cant speak on customizations etc since they are not company supported.
I do not know what you modified etc so I cant comment there. But for instance if your running say the older 4.03 code and our current code is 4.1 which might fix some issues with prior code then the proper solution is you to update your code.
More often that not if your reporting a specific issue from an older version that might have already been addressed then it is one of the fixes that would be provided in updated code. The search feature in our latest code is different than what your reporting which is why I know your running an older version. We changed the search in 4.1 to allow complete compatibility with the new SEO
Here is a link to the changed files between 4.03 and 4.1 PhotoPost Classifieds 4.1 Released 09-13-2010
if you have any files modified on those then you need to address accordingly but those are the changes files you need to upload.