My relationship with IB has eroded over the past couple of years, when the CFE goes 24 hours it might be time to stop doing business with them completely. I can imagine the horror if the spoos drop 50 handles overnight.
I had no issues with 2 other brokers i deal with. IB's MtM logic is fairly unbalanced during turmoil or system issues but there arent many options out there for someone who doesnt go the PB route.
A quick Google search will return tons of people reporting the same. Here's one interesting thread: http://www.elitetrader.com/vb/showthread.php?threadid=210359 On page 3 an IB official clearly states that they reserve their rights to liquidate after hours, but they do not do it under "normal conditions", whatever that means. Always assume the worst.
The bad marks were in Sept VIX call options on Friday, August 10th 2007. Liquidation of the forex positions took place Sunday August 12th. IB, at the time, apparently valued the calls at the higher of closing mid or intrinsic (ITM) value, but they calculated intrinsic off of the spot VIX, not the futures. Sept Futures settled at 23.63, spot at 28.30, so calls were marked well above true closing prices. I was short 100 of the Sept 25 calls, which IB considered 3.30 ITM even though they were actually 1.47 OTM. I never throw anything out as far as records go, so I still have all my screen-grabs, support chat logs, and emails relating to the incident.
Based on my understanding they will liquidate stock from 9:30 to 4, but futures get liquidated all trading hours.