Affinity Engines filed suit against Google. Orkut Buyukkokten, and ex co-founder of Affinity Engines and engineer, stole code that he had written for Affinity Engines [after he left, of course] and basically handed it to Google for use in Orkut. If I remember correctly it was such an obvious rip-off because of identical flaws in the code in both the Affinity Engines and Orkut systems.
The lawsuit has yet to be resolved that I am aware of. I would bet the problem is one of many bugs that caused numerous shutdowns that I read about awhile back. It's still beta, afterall.