It sounds to me as if the setting for the scanner driver is wrong. You can use this printer's scanner in a peer to peer network situation, but not in a network shared environment.
First you need to get the printer's IP address.
Press the Menu or Menu/Set key on the printer, and select Network or LAN. Select Network or LAN > WLAN or Wired LAN > TCP/IP > IP Address
In Windows 7 Click Start and type "scan" in the search field. Then, click 'View scanners and cameras'. Select the scanner and click 'Properties'. If the User Account Control screen appears, click 'Yes'.
Click 'Network Setting' tab and select 'Specify your machine by address'. Now enter the IP address you obtained, Click OK.
Be warned that you may need to disable the firewall,or adjust its settings to get the scanning facility to work.