我通过 Visual Studio 2010 创建了一个 InstallShield 安装程序，它具有 .NET 4 框架作为先决条件。
在安装过程中，一些用户收到错误消息，通知他们在下载 .net 安装程序时发生错误。
我使用 debuglog 命令行参数运行安装程序并得到以下信息：
7-24-2012[12:16:07 PM]: PrereqEngine: file,251743DFD3FDA414570524BAC9E55381,<ISProductFolder>\SetupPrerequisites\Microsoft .net\4.0\Full\dotNetFx40_Full_x86_x64.exe,http://download.microsoft.com/downlo...ll_x86_x64.exe,,, -- Successful,
7-24-2012[12:16:07 PM]: PrereqEngine: execute,dotNetFx40_Full_x86_x64.exe,/q /norestart,/q /norestart,1641,3010,, -- Successful
7-24-2012[12:16:07 PM]: PrereqEngine: dependency,<ISProductFolder>\SetupPrerequisites\Windows Installer 3.1 (x86).prq, -- Successful
7-24-2012[12:16:07 PM]: PrereqEngine: dependency,<ISProductFolder>\SetupPrerequisites\Windows Imaging Component (x86).prq, -- Successful
7-24-2012[12:16:07 PM]: PrereqEngine: dependency,<ISProductFolder>\SetupPrerequisites\Windows Installer 3.1 for Windows Server 2003 SP1 (x86).prq, -- Successful
7-24-2012[12:16:07 PM]: PrereqEngine: dependency,<ISProductFolder>\SetupPrerequisites\Windows Imaging Component (x64).prq, -- Successful
7-24-2012[12:16:07 PM]: PrereqEngine: dependency,<ISProductFolder>\SetupPrerequisites\Windows Installer 3.1 for Windows Server 2003 SP1 (IA64).prq, -- Successful
7-24-2012[12:16:07 PM]: PrereqEngine: dependency,<ISProductFolder>\SetupPrerequisites\Windows Installer 3.1 for Windows Server 2003 SP1 (x64).prq, -- Successful
7-24-2012[12:16:07 PM]: PrereqEngine: dependency,<ISProductFolder>\SetupPrerequisites\Windows Installer 3.1 for Windows XP (x64).prq, -- Successful
7-24-2012[12:16:07 PM]: PrereqEngine: Id,{32D7E3D1-C9DF-4FA6-9F9B-4D5117AB2917},http://saturn.installshield.com/is/p...ites/microsoft .net framework 4.0 full.prq, -- Successful
7-24-2012[12:16:07 PM]: PrereqEngine: behavior,Optional,,Reboot,2,Failure,
7-24-2012[12:16:07 PM]: PrereqEngine: Lua,
7-24-2012[12:16:07 PM]: PrereqEngine: Hidden,
7-24-2012[12:16:07 PM]: PrereqEngine: MsiProgress,
7-24-2012[12:16:26 PM]: DownloadFiles: An error occurred while downloading the file http://download.microsoft.com/downlo...ll_x86_x64.exe. What would you like to do?
7-24-2012[12:16:30 PM]: Prerequisites returning 2
如果我在同一台计算机上打开 Internet Explorer 并从该日志文件将 URL 粘贴到 .net 安装程序，它会毫无问题地下载。
关于可能的原因或进一步调查的步骤的任何想法？