Quote from Option Trader:
They merely flash a warning before you open a 4th trade, that if you open the 4th trade, you won't be ab le to close it till the 5 days go by.
http://www.interactivebrokers.com/en/trading/marginRequirements/margin.php?p=d&ib_entity=llc
It specifically says, (in the FAQ link in the above link), you may CLOSE a positon, after violating the PDT rule.