Q:

ClickOnce: The required version of the .NET Framework is not installed on this computer

I have been getting the error "The required version of the .NET Framework is not installed on this computer." (Event Id 4096 in Event log) when trying to install a VSTO application from both a ClickOnce deployment and a local copy. This is interesting as the .NET framework is installed (on my 32bit Windows 7 PC) and the VSTO application was developed on the self same machine (and works in Visual Studio 2008).
Does anybody has an idea why I could get this exception?

Name:  From:
  http://localhost/BlaBla.vsto
"The required version of the .NET
  Framework is not installed on this
  computer."
************** Exception Text ************** Microsoft.VisualStudio.Tools.Applications.Deployment.InstallAddInFailedException:
  "The required version of the .NET
  Framework is not installed on this
  computer."    at
  Microsoft.VisualStudio.Tools.Applications.Deployment.ClickOnceAddInDeploymentManager.InstallAddIn()
  at
  Microsoft.VisualStudio.Tools.Office.Runtime.SolutionInstaller.<>c__DisplayClass7.b__0()

A:

After checking of the obvious causes (see comments) it seems to leave Windows 7 as the cause. Despite lots of people 'switching' to Win7 it's still a beta. 
A few points come to mind:

can you check the clickonce install on XP or Vista?
do you have AutoUpdates turned on? 

