MB: I think Chris is on the money.
If you choose to use George's solution (which will work also, but means you need to change all of your clients), still keep in mind that each VIP has a TCP profile bound to it and TCP behaviors are tunable per vip. By default we use a 5 minute (300 seconds) idle timeout value. To fix this, simply create a new TCP profile for this virtual server and change the idle timeout to something that makes sense for your environment.
This is a common issue for FTP as well - the control channel will time out during large transfers. But I digress.
-Matt