Request Failed Error When Starting Microsoft Excel

You accessed IBM Cognos 8 Controller at least once from the same client computer, and are now trying to start Microsoft Excel. A request failed error appears followed by a long error message related to security.

A possible cause may be that the client computer has two versions of Microsoft .NET Framework installed and Microsoft Excel is configured to access a version not supported by IBM Cognos 8 Controller.
You must verify that Microsoft Excel is configured to use Microsoft .NET Framework v2.0.50727.

Steps to Configure Microsoft Excel to Use the Current Version of Microsoft .NET Framework
On the client computer, go to the Microsoft Office installation directory, such as C:\program files\Microsoft Office\Office11 and look for the Excel.exe.config file.

If the Excel.exe.config file exists, open the file in a text editor and verify that the version statement is exactly as follows:
supportedRuntime version="v2.0.50727"If the file does not exist, use a text editor to create a new file named Excel.exe.config and copy and paste the following lines into the file:

<supportedRuntime version="v2.0.50727"/>