Visual Studio 2008 abruptly closes when I try to build an Outlook 2007 Add In. My workstation is configured as follows: * Windows XP Professional * Outlook 2007 SP1 * Visual Studio Team System 2008 Development Edition * Microsoft .Net Framework 3.5 Originally I thought this was a code problem in my add-in, or that perhaps my PC needed to be rebooted. This morning I powered off and rebooted. Here are the steps to replicate my problem. Additionally, I read that Outlook needed to be closed before building an add-in. I also tried that, but it still did not work. I suspect that this may be related to the registry settings that VS 2008 attempts to make when it builds an Add-In. Here is an excerpt from Professional C# 2008 that lead me to this hypothesis. Managing Application-Level Add-Ins One of the first things you will find when you create an application-level add-in is that VS carries out all the steps necessary to register the add-in with the Office application. This means that registry entries are added so that when the Office application starts, it will automatically locate and load your assembly. If you subsequently want to add or remove add-ins, then you must either navigate through Office application settings or manipulate the registry manually. Steps to replicate my problem. 1. Boot computer and do not open Outlook. 2. Open VS 2008 3. Select File > New Project > Visual C# > Office > 2007 > Outlook 2007 Add-In. 4. Choose the default name and then OK. 5. Select Build > Build OutlookAddIn1. The build output window briefly appears and displays the following. Note this is from a screen shot, and I was unable to read all the contents of this. Build started: Project OutlookAddIn1, Configuration: Debug Any CPU c:\WINDOWS\Microsoft.NET\Framework\v3.5\Csc.exe /noconfig /nowarn:1701,1702 /warn:4 /define:DEBUG;TRACE /reference:c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Accessibility.dll /reference:"C:\Program Files\Microsoft Visual Studio 9 After that Visual Studio 2008 abruptly closes. This problem also occurs if VB.Net is selected in Step 3. And it occurs if Outlook 2007 is opened before opening VS 2008. Some relevant project properties are below (Project > OutlookAddIn1 Properties). If you need something else from this let me know and I can respond. Target Framework: .NET Framework 3.5 Build Config: Active (Debug) Platform: Active (Any CPU) Define DEBUG Constant: Checked Define TRACE Constant: Checked Warning Level: 4 Treat warnings as errors: None Output Path: bin\Debug\ Generate serialization assembly: Auto Perhaps there is something else I need to install in VS, like a patch or plug in. Thanks for your help.