I can't really help much without seeing the list because we would waste time trying to chase ghosts.
Look into the list and see if indeed you have 951 lines of text (1st line is the header), rest of 950 are the actual users.
Look for duplicates in the list and in the import log.
Try another list, smaller.
I doubt the import would go so wrong if your list indeed has 950 records and there are no dupes and they are all valid., so check the file again and again.