Add a new folder on a network drive to your Documents library in Windows:

Libraries->Documents->right click -> Properties -> Include a folder -> select a folder on a network drive -> accept -> make it default.

In this scenario, a call to QDesktopServices::storageLocation(QDesktopServices::DataLocation) returns the incorrect path.

This seems to be because inside QDesktopServices::storageLocation, on line 197, you're making this call:

SHGetSpecialFolderPath(0, path, CSIDL_LOCAL_APPDATA, FALSE)

this could possibly be

SHGetSpecialFolderPath(0, path, CSIDL_APPDATA, FALSE).

The MS document (http://msdn.microsoft.com/en-us/library/bb762494%28v=VS.85%29.aspx) says that CSIDL_LOCAL_APPDATA is for local (non-roaming) applications. So it's no surprise the call fails when it sees a network user directory.