Eric, at this point, I'd suggest you ignore this as I think it's pretty clear it's not a NWC issue.
A simple test: try running NWC as admin (just once), and test the backup mechanism. If it works, then you likely have a permission issue.
You indicated that there was no problem on XP, which raised my UAC suspicions. Unless you have UAC disabled, admin elevation might yield new info.
Page created in 0.054 seconds with 24 queries.