Error code 66A on a standalone. Turns a network connection error code into a corruption error code.
# for hex 0x66a / decimal 1642 :
# The upgrade patch cannot be installed by the Windows
# Installer service because the program to be upgraded may be
# missing, or the upgrade patch may update a different
# version of the program. Verify that the program to be
# upgraded exists on your computer and
# that you have the correct upgrade patch.
# 1 matches found for "66A"
Please download the following tool: Automated cleanup tool to remove the .NET Framework 1.0, 1.1, 2.0, 3.0 and 3.5 - Aaron Stebner's WebLog - Site Home - MSDN Blogs
Use it to remove .net Framework 4 only. Once it has removed .net Framework 4 ONLY, restart your computer and download the .net Framework Web Installer from here, and install it: Download details: Microsoft .NET Framework 4 (Web Installer)
Restart your computer again, and open Windows Update. Even if it shows you updates to install already, click "Check for Updates". Once it has checked, install anything available, and come back to us on the success of this.