I was using model builder for extraction by mask. The directory I am working from has 20 years worth of monthly temperature rasters, in .bil format, and is about 860 MB, so it's kind of big, at least to me. Now, when I open the model builder window, every time that I link the directory to the "Rasters" iterator object, ArcMap (10.2.1) crashes and I have no error message to tell me what happened. The thing is, I already ran multiple extractions successfully on 3 similar directories in the same way with no problems. Now, I've tried several times since the first crash. I've restarted my computer several times. I tried just one extraction with one of the files and it worked. I don't know what is causing model builder's uncooperative behavior all of sudden. Is there some kind of cache I need to clear out or are there any other guesses?