What did Arafat die of?

As I watched today his funeral on TV and then went to see the protests after the Friday sermon at Al Azhar mosque (which were surprisingly small, but then again the mood of the day was sadness rather than anger), this question kept coming back: what is the cause of Arafat's death. As this story on the rumors that he was poisoned by the Israelis -- a rumor started by Hamas -- shows, we still don't know. I wouldn't give much credence to the poison theory, but I think we need to know what happened. Did they pull the plug on him? Who made that decision? Or was it simply the result of the brain hemorrhage he was suffering from? If these questions aren't answer, the rumors are just going to keep spreading.