Why am I having this problem importing photos from iPhone to iPhoto? I'm getting the error

Error downloading image.
iPhoto cannot import your photos because there was a problem downloading an image.


when I "Import All..." from my iPhone. Trying to import individual images I get

The following file cannot be imported. (The file is in an unrecognized format.)
IMG_0301.JPG


In the past I've been able to do this, so I don't know why I'm getting grief now. Anyone have any suggestions?

To help describe the problem I've created a screencast: http://screenr.com/CLr
I seem to have resolved the issue by connecting my iPhone 4 directly into my MacBook as opposed to using a USB hub which I connect everything to.

edit: I also found this to be the case after a long term problem with importing photos/films from my iPhone 5; it was intermittent and buggy, but I was using a simple USB extension cord from behind my computer and eventually removing; because of this, this answer solved the entire issue.