If you cannot copy then there is a problem with your scanner. You will have to service it with whatever repair options are available. Try HP first if you are under the warranty. Copy has nothing to do with network connections or software. It should always work for you unless there is a physical problem on the printer.
In regards to your printer going off the network chances are your router is losing communciation with it due to normal timeout policies. It is normally best to configure the a printer to a Static IP Address to avoid these kinds of normal cleanup proceedures. Next time this happens then print off a configuration page and check the IP to confirm it is actually connected or not.