As I understood the incident, two engines suffered a partial thrust reverser unlock/deploy situation*, which caused the automatics to stow the L/E lift devices, possibly only until the gear left the ground, but enough to seriously reduce the lift generated. This was resolved by "firewalling" the throttles to keep her in the air long enough for a circuit.
This is only from reading the 2009 thread though - any further details would be good to know.
This kind of thing isn't limited to digital automation though - it can happen mechanically as well. The infamous 737 rudder PCU issue was a result of a combination of wear to the valve and very low temperatures causing an uncommanded reversal, and the AA191 DC-10 crash was a result of uncommanded slat retraction as a consequence of engine pylon failure.
* - so maybe "failure" was the wrong word
Last edited by DozyWannabe; 26th Jun 2010 at 10:54.