I heard from a customer who ran into an interesting issue during Visual Studio 2008 setup that I hadn't seen until now.  I wanted to post a description of the issue, how we diagnosed it and how to work around the issue in case anyone else runs into a similar issue in the future.

Description of this issue

On this customer's system, the Web Authoring Component prerequisite component failed to install and Visual Studio 2008 setup failed as a result.  There are many possible causes for this type of failure, so we need to dig deeper to try to find the exact cause of the failure.

How to diagnose this issue

Visual Studio 2008 setup runs the Web Authoring Component setup package in silent mode, so the next step is to take a look at the log file for the Web Authoring Component to narrow down the issue further.  This issue will cause the following information to be written to the log file for the Web Authoring Component (named %temp%\SetupExe(*).log):

Catalyst valid path check failed: The path c:\Program Files\\Microsoft Web Designer Tools is invalid

Notice that there is an extra backslash between Program Files and Microsoft Web Designer Tools in this log file.  I had the customer check their registry and we found that the path to the Program Files folder was being stored there with a trailing backslash, but Windows typically stores the path to Program Files and other system folders without trailing backslashes.

In this scenario, it is also possible to run Web Authoring Component setup directly from <VS install path>\WCU\WebDesignerCore\WebDesignerCore.exe in order to see a specific error message instead of looking at the log files.

How to work around this issue

To work around this issue, you can change the value that Windows uses for the Program Files directory on your system by doing the following:

1. Click on the Start menu, choose Run, type regedit and click OK
2. Locate the following registry value:
   
[HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion]
ProgramFilesDir


3. Remove the trailing backslash from this ProgramFilesDir registry value
4. Close regedit and reboot the computer
5. Re-run Web Authoring Component setup from <VS install path>\WCU\WebDesignerCore\WebDesignerCore.exe
6. Look at %temp%\SetupExe(*).log and verify that installation succeeded this time
7. Re-run Visual Studio 2008 setup to complete installation

One note about this issue - the Web Authoring Component setup package uses the same setup wrapper as the Office 2007 family of products.  It appears that other Office 2007 products may have similar installation errors if the ProgramFilesDir value has a trailing backslash like this.