Windows Client times out while downloading layout and does not retry

I am having problems with the Windows client showing 'Required File status: Error: The operation has timed out’
This appears after roughly 5 Hours of downloading a large layout (4Gb) and the client seems to give up trying to download at this point. The error is seen in the Client Information window.
What is likely to be causing this and is there a time out value I can increase somewhere.
I am using Server and client V1.7.5

The first thing to do is try to upgrade - we are on 1.7.8 now and this may well have been resolved.