What does the two Red Rings Of Death represent?

Well, My Xbox has the two Red Rings Of Death. The disc tray would not open fully but can close back fully. I tried to use a paper clip (not using the guide here) and manage make it come out and go in successfully. Then, the two Red Rings Of Death showed up. I thought it over-heated and left it alone for a day. Now, it sometimes (but rarely) has problem closing back fully while the disc tray cannot go out fully. I miss playing Halo Reach. Help! =(

placeholder text for bug in Chrome