This is Windows 7 with python 2.7
I have a scrapy project in a directory called caps (this is where scrapy.cfg is)
My spider is located in caps\\caps\\spiders\\c
I had the same issue. When i was using "scrapy list" in cmd the command listed the spider name i was getting the error for, in the list, but while i tried to run it with scrapy crawl SpiderName.py, i used to get Scrapy spider not found error. I have used this spider before and everything was fine with it. So i used the secret weapon, i restarted my system and the issue was resolved :D