I have uploaded 22 different themes today. Many of them do not show an image in the Presentation page. Of those that do appear, whenever I activate one, the site does not display at all. I can't even switch back since the page won't display. The only way that I have regained the site was to delete the offending theme's directory on the server. Then I get the default theme again.
How is this possible? How can every theme be defective [I really don't this is true but I have no other way to explain it]? How can I get a stable installation?