It also says "NS_ERROR_STORAGE_CONSTRAINT" so you might want to check this:
https://stackoverflow.com/questions/349 ... in-firefox
I see that error in Chrome also, but it still works fine in both browsers. It's a var not defined. Something with a folder or something in a folder. I can diagnose by basically eliminating folder by folder and finding exactly what item is causing the error ... Here, there is nothing wrong though as it works in both browsers.
What do you mean "loads half empty pages"? Can you give me an example of exactly where you are and where you click to see this?