Re: category page disappearing... sometimes
This isn't a bug. You have to have more than one product in a category.
Or you can change the setting in Admin -> Configuration -> Layout settings -> Skip 1-prod Categories
Skip single-product categories
If this option is set to True, then if the customer clicks on a link to a category which only contains a single item, then Zen Cart will take them directly to that product-page, rather than present them with another link to click in order to see the product.
Default: True
Please do not PM for support issues: a private solution doesn't benefit the community.
Be careful with unsolicited advice via email or PM - Make sure the person you are talking to is a reliable source.