Dave Lee , May 23, 2011; 11:38 a.m.
Mike, try the way I work with raw files. Do not import them into iphoto at all. Select only the JPG photos and import them, and then manually move the raws from the card into a folder on the desktop.
If you are exporting to the desktop from iphoto, make sure you select "Original" in the type. Not anything else. But I avoid the problems you are experiencing by just not importing raws into iphoto.