Have you tried just pluggin your phone via USB into your laptop with win7 to try using your phone as removable storage for media access.
Im think that this may be an old driver and you need to find an updated version.
Drivers are as far as i can see are only updated to vista. Try using the vista driver for your phone..
click the link below to get it.
http://za.samsungmobile.com/support/softwaremanuals/software.do?phone_model=SGH-D900i
First though uninstall the old software before installing the new.
Goto control panel, programs and then uninstall programs to delete the old one...