Some faces go randomly invisible

I have some problem , while creating a model , i added a new object for creating hair and set it on proper position , i added mirror and subsurf modifier. after extruding it , it does create faces , but random faces go invisible depending on angle from what im viewing it , it is only happening for that object (i added a circle then deleted all vertices and created other circular obj with snapping tool )
it does not happen to any other part of model , i mean other objects faces look as they should , only in this its problem , any idea’s why this is happening ?
I have i3 M380 and internal graphics , i believe its Intel HD 2000 , im using Ubuntu 13.10 and Blender version is 2.69 r60991
Images attached below


first of you may want to update to 2.70… second it probably has to do with the normals… if you go into the mesh tab in the properties section, try enabling normals double sided… maybe also try making the normals consistant (edit mode, select all, ctrl n)

Thank you , i never had such problem before , i always used to recalc normals only when it looks deformed after applying smooth , here it solved problem :smiley: , i couldnt find double side normals option though , but i dont need it now , i need to close that mesh anyway