VSTO solution using ClickOnce via IIS 6 fails to download manifest

I have an Office solution for Word 2007 that I publish using ClickOnce. When I publish it to a local directory, I can install the .vsto file and everything works. When I publish it to our web server, though, I cannot install it. The error I get is:

Downloading file:///C:/DOCUME~1/Dave/LOCALS~1/Temp/Application Files/MyApp_1_0_0_0/MyApp.dll.manifest did not succeed.

I have been Googling for most of the day, and have already tried the following:

• Added the correct MIME types to IIS 6 config (as described here and here on MSDN).
• Created a test certificate, imported it into my trusted root authorities, and signed the app with it.
• Published the solution to a network share and tried installing from there. It worked fine.
• Tried accessing t开发者_如何学Pythonhe MyApp.dll.manifest file directly from the web URL. The browser is able to find the file just fine.

What am I missing? Thanks.

Make sure that Windows Installer 3.1 is installed on the end-users PC. If it's not, you may want to add it as a prerequisite to your application.

Also, you may want to check and see if the application is installed from the Windows Add/Remove Programs screen. If it is in the list, you may need to uninstall the application, first. I know, you're probably thinking 'But the application hasn't been installed yet.'

Quite a few application that are published via ClickOnce. ClickOnce works great most of the time, but every now and then I see users who run into hiccups similar to yours when they try to initially install the application. The best solution is to usually uninstall all prerequisites, reboot, manually re-install the prerequisites (not from the ClickOnce setup.exe file) and then launch the application.

Some of those steps may not be necessary but it tends to fix the problem nearly every single time.