Q: error -50

I am getting the following error message as I am trying to download the film "A Good Year" from the iTunes store.

"  There was a probem downloading "A Good Year / Ridley Scott."  An unknown error occurred (-50).  "

Please check that the connection to the network is active and try again.

I have downloaded 954.5 MB of 1.60 GB.

Can anybody help please?

Many thanks.