I installed the Shopp plugin and then Contact-Form-7. When I tried to activate the contact form plugin, I get a white page. I reversed the order of plugin installation and same problem.
I could not get both to run at the same time. Not only contact form, but other form plugins have this same problem. But the problem is not in the plugin themselves. Something wrong with my wordpress database or envornment. Because when I installed the two plugins in a fresh WP environment, it works fine.
How can I debug what is wrong with my WordPress plugin system? And how can I get it to display some error message instead of a white page?