Hi Maryad,
Thank you for using Vista Support forum,
You might want to try and run Windows Update first to get the latest .NET Framework update there is for your system.
I been looking around and this error seem to mostly relate to Quickbook 2009. Do you have the program installed by any chance? If yes, you should try to remove the program temporary (make sure you have the install media to reinstall if you do).
Let us know if you need further assistance,
Kevin
Microsoft Answers Support Engineer
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