Read the info at the above link re that 646 Error Code.
Compliments of: David_O - Support Engineer
This problem occurs when the Windows Update agent file Wups2.dll is registered incorrectly in the registry. Because the registry files that correspond to the Wups2.dll file are missing, update installations are unsuccessful. There are two methods to
resolve this issue, use method one first and if it did not resolve your issue, proceed to method 2
Method 1: Register the Windows Update files
1. ClickStart and then type notepad in the Start Search box.
2. ClickNotepad in the Programs list.
3. Copy the following commands, and then paste them into the opened Notepad window:
5. Right-click the Register.bat file, and then clickRun as administrator.Collapse this imageExpand this imageIf you are prompted for an administrator password or for a confirmation, type the password or clickContinue.
6. Try to install updates again.
Method 2: Download and install the Windows Update agent
For more information about how to download and install the latest Windows Update agent, click the following article number to view the article in the Microsoft Knowledge Base: