I have been having this problem since version 1.6. I am now on 1.7.
I have switched servers and this is a clean install of 1.7.
I am using PHP Version 5.3.14
When I go to category I get in admin I get
The website encountered an error while retrieving http://emsstuff.com/index.php/admin/catalog_category/index/key/92c1a3f921b654a96ee9545b8e5978d6/. It may be down for maintenance or configured incorrectly.
Here are some suggestions:
Reload this webpage later.
HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request.