Solution:
1, Start-Run-type "REGEDIT", find the following key: value HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products
Delete the corresponding Autocad subdirectory under this directory.
2. Find the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products Delete the key 7D2F387510074080002000060BECB6AB.
3. Delete the CAD installation directory.
4. Reinstall CAD2012:
1>. Start the installation of Autodesk AutoCAD 2012, point to try the installation
2>. Complete the installation and restart CAD.
3>. Click Activate, enter the serial numbers: 666-69696969, 667-9898989898, 400-45454545 Password: 001D1, select "I have an Autodesk Activation Code"
4>. The activation code is incorrect and the activation fails.
5>. Reactivate, start the register, paste the application number into Request, click Generate to calculate the activation code, and click the Mem Patch button.
6>. Copy the Activation Code from Activation to the Enter Activation Code field, and you will be prompted to have a fully registered Autodesk product.