Step 1: Uninstall .NET Framework components
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1. Click Start, click Run, type "appwiz.cpl" (without quotation marks) in then Open box, and then click OK.
2. Select all .NET Framework related entries from the programs list and click Remove to uninstall them. If any error message is encountered during the uninstallation, please ignore it. If there is no error, steps 3-5 can be skipped.

3. Please download the Windows Installer Cleanup utility from this link and save it to the Desktop:

http://download.microsoft.com/download/E/9/D/E9D80355-7AB4-45B8-80E8-983A48D5E1BD/msicuu2.exe

4. Double click the msicuu2.exe file and follow the wizard to install this program.
5. Run the utility from Start and choose All Programs, then Windows Install Clean Up.
6. Select all .NET Framework entries from the list and click Remove.

Step 2: Reinstall .NET Framework

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Please download and install .NET Framework 2from the Microsoft download center