Do you believe the Planet X theory?

[UFO Finder]

I just found out about this Planet X theory that there is another planet in our solar system with a huge elliptical orbit which only crosses into our normal solar system every few thousand years or something like this.  They say that there are living beings on this Planet X and many accounts in history support the Planet X theory.  It's truly fascinating, if you never heard about it you should check it out.

[Seb]

I personally don't believe the planet X theory. I've read 3 books by Zecharia Sitchin (if I remember correctly... it's been along time) and one of these books was about this planet and the so-called Annunaki. Most scholars, who also study the Sumerian texts, come to completely different conclusions from those of Sitchin. He seems to be the only one claiming the ancient Sumerian texts speak of this tenth planet and its inhabitants, while all the others interpret it much differently.

I don't rule out the possibilty that there could be another planet or more out there in our solar system. But I'm skeptical that a planet ever comes into the orbits of the inner planets as is claimed.