Insert feature causes Out of memory exception

Hi!
I'm developing the 3D modeling GIS software. For 3D city models i use generated from vector data building models and 3d files (Google Earth and SketchUp) with geographic coordinates within. I import such files' geometries with IImport3DFile and store them in multipatch featureclass in file geodatabase.
At last I recieved an exception "Out of memory" during IFeatureCursor.InsertFeature. Have to say that there was no such a problem before (with other files). Error appears constantly after processing definite number of files. Geometries i load from them are correct, i processing their footprints and if i don't save them to my featureclass i process them all with no exceptions. After the exception appears program can't work properly at all until restart (looks like ArcObjects crash).
How you could understand i use insert cursor with featurebuffer. Tried edit sessions, load mode for featureclass, direct write with WriteFeature and so on... No differences. May anybody help me? Any suggestions?
Sorry for my English )