I clean-installed Zen Cart v150 today. In the setup, everything returned fine (htaccess, CHMOD settings, everything) on Apache with PHP5/MySQL/CURL.

However, when attempting to add an item to the cart, setting up a customer account, or logging in as a customer, the main_page 404's.

No addons, no templates, just a standard install that causes this error. I've searched, and while other people have had this problem, I can't find a solution to it; they seem to just disappear or the error resolves itself randomly.

I have also deleted the files/database and started from scratch with the same problems occurring.

Thanks,
Pat