Have spent the last 2 days trying to get the RTM version of Visual Studio 2008 to install and what an experience that has been. Kept getting an error during the overall install process with the Web Authoring Component and the error given was:-
setup.exe:  ISetupComponent::Pre/Post/Install() failed in
ISetupManager::InternalInstallManager() with HRESULT -2147023293.
Now the googling started as I tried to work out what the problem was, all sorts of offerings were made and I tried most of them. Finally settling on extracting the web authoring component to a temp directory and running its setup out of the combined Visual Studio installer. This indicated that some Office 2007 Beta component was installed which was hindering the installation. So working through the various Office add-ons I had installed, previously I have had this error due to the PDF/XPS add-on and the Expression Blend betas. Well the PDF add-on is now the release version and I had already removed Expression Blend. After a few attempts it turned out that the Outlook 2007 Calendar Printing Assistant was the culprit, and once removed the install proceeded to complete.
Now I ask why couldn’t the combination installer tell me that in the first place, without trying to install it manually I would still be looking for a solution. If you are going to create combination installers which roll-up a whole host of components and install them together then you need to make sure that decent error messages are either passed back to the main installer or at least logged somewhere for further diagnosis.