After reading The Kite Runner I want to know more. What specifically happened and more importantly why? Why did the Russians invade? Why did the problems continue afterwards?
Afghanistan was always a weak state and rather chimerical, as its borders are not aligned with ethnic composition. Government in Kabul always has difficulties controlling tribal areas and not much say outside of Kabul area.
In 70s two processes collided: growing islamic radicalization (interestingly, many fundamentalist organizations orginated from Kabul University - such leaders as Hekmatiar, Rabbani were either students or professors) and growing demand for modernization (mostly from growing middle class and from military officers, who were trained abroad).
Current period of unrest started when Daoud overthrew his 1st cousin the king Zahir-Shah in 1973.
Why did the Russians invade?
causes and consequences:
http://www.reddit.com/r/AskHistorians/comments/202x4n/causesconsequences_of_the_afghansoviet_war/