In Magento admin panel I can't access existing categories: There is always a blank category page showing (New Root Category), nothing happens when I choose existing category from the category tree. Everything else is working fine. The problem started when the client upgraded to a bigger web hotel, but the host is saying there's nothing wrong with the server settings and the problem is in Magento. How can I try to fix this?
In my experience a blank page is usually caused by PHP running out of memory. Do you have logging enabled, and did you check the server (usually Apache) error logs?
Did you resolve this? I'm getting this exact behavior. Go to Manage Catagories, and click on a category. All you see on the right is New Root Category.
info shows 1G memory.