Sometimes there may be something on one or more of your slides in the project that will be causing the publish to fail.
To isolate where the issue is located, take a copy of your project to use for testing, and hide different groups of slides before trying again to publish. If by hiding some group of slides you can now get the project to publish, use a process of elimination to find the slide where the issue is located and then go through that slide dragging one object at a time into the scrap area before republishing again.
If this is the issue preventing you from publishing then eventually you should be able to locate the offending slide or object.