I will gladly do my best to help you but I am going to assume the reason nobody has responded is due to the fact this can get very complicated. I hope I can make this as simple as possible but I will have to ask you a few questions first in preparation of steps to come. Please answer all of these for me so I can give you the best advice needed to resolve this.
1. What is the operating system of the PC connected to the printer? Be specific please (in case there is a firmware update specific to your system type (ex. Windows 7 64-bit, Windows Vista 32-bit, etc)?
2. How is the printer connected to the computer (USB. Ethernet or wireless)?
3. You are referring to the Officejet J4680, correct?
4. When you scan the second page in and it fails, do you also see 4, [2,7,800-40007]?
5. What brand of PC do you have (HP, Dell, etc)?
6. Are you trying to run your second scan from the scanner glass or the automatic document feeder on top?
7. I know this is due to an error with the scan application on your computer based on the error code the first person who posted offered, so can you scan multiple pages using Windows Fax and a Scan or Paint?
I know that is a lot of questions and I want to provide the easiest steps possible at first. But if it gets complicated I won't have to ask them later. :)