Why can't I import photos from iPhone? What can I do to fix it?

I'm not able anymore to import photos from iPhone 4s nor from my iPad 1.

It's quite annoying, I've been following many tips, but nothing works.

Does anyone know how to fix it?

Many thanks in advance,

JR

Error messages

From iPhoto, I get

Error dowloading image

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

From Image Capture:

Import error

An error occured while importing. x items were not imported:

From Picasa:

Error occurred attempting to dowload the file. (ICA error code -9912)