On the WeblogTools Collection blog today there's a new post from Ronald Huereca with a tip about manually turning off and on your WordPress plugins if you get into a bind and need more than the web-based interface can do.
There may be times in WordPress where you would like to load the WordPress environment manually, and prevent plugins from loading. [...] To further give justification for this technique, I had a major plugin conflict with another plugin. My Ajax Edit Comments plugin had failed to work for one of my clients. After doing some troubleshooting, I determined it was a plugin conflict with "xyz" plugin.
He admits that the technique is a "hack" but can be quite useful in the right situations. The process involves changing your wp-settings file to define the "WP_INSTALLING" constant then the plugins can be manually loaded as needed instead of automatically. This can help narrow down where an issue is (sometimes) faster than enabling/disabling them and guessing.