Does the Virus XMRV ring a bell?
It didn't for me either. This is a retrovirus that latches onto your DNA. There are several articles about it that are more informative than I can be. Isn't that sort of scary? At least then we might be onto something as far as a cause for this disease is concerned.
Here is a great link to look at:
http://www.virology.ws/2009/10/15/xmrv-and-chronic-fatigue-syndrome/