Content of the image frame turns grey while dragging

I'm working on Mac (OS X 10.8.4) and InDesign CS6.

For some weeks now I have had weird problem. While dragging the picture around the content turns solid grey Inside the image frame but the rest of the image is still visible outside the frame (the lighter version of it, of course). It is very inconvenient and annoying.

Is there something I could do to see again the image INSIDE the frame while positioning the picture?

thank you

Evelin