Strange negative quality
 

Dear all, I am trying to mesh an airfoil ( 2D ) with a split with ICEM 11.
I have created the Parasolid file is Solidworks 2010 and imported the file to ICEM.
every thing seems to be alright , and just when i create the hexa mesh, I can see at one line related to split edge at the suction surface the quality is negative.
This is because the ICEM creates and considers some very small imaginary small surfaces that do not exist in the geometry( in reality) and you can not see them physically, but they exist in mathematical considerations for the geometry.
this imaginary non existing areas ( and curves) although are not being associated with any edges, but absorb some edges to themselves ( by the software) and make some elements with negative qualities.
A i told you , investigation of the geometry shows no sign of such surfaces and curves, but observation of the elements shows those badly twisted elements with negative quality.
I want to ask has anyone faced this problem before and how to solve it.

thanks