The topic of whether or not virus's are alive is hotly debated still as far as i am aware. However i think that the main problem with the definition of alive is that we are simply composed of molecules interacting in various ways, this happens in a test tube in a chemistry class. I reckon alive is in the same class of vague definitions such as species etc etc Its all rather fuzzy.
Unseul
Give a man a fire and he's warm for a day. Set a man on fire and he's warm for the rest of his life....