Windows 7: Security Essentials Install error 0x80070643

Error code 0x80070643 comes up whenever I try installing Microsoft Security Essentials. I had Security Essentials installed earlier but after I used the .net cleanup tool (since I had a problem with .net) it shut down and wouldn't start back up again, so I uninstalled it.

I have also tried installing AVG Internet Security but it comes up with AVG error 0xC0070643 with error message: General internal error.

I think my computer had .net framework 3.5.1 installed before but it won't install either. I got .net framework 4 to install but it didn't help and wouldn't uninstall or repair and the updates wouldn't install for it either (windows update error 66A and 643).

Please help me

It appears that remnants of the first Essentials is still present. Try downloading ccleaner, run it, boot and then try to install again.
http://www.piriform.com/CCLEANER
If that does not work, with system restore, go back to before the uninstall. Then download revo and uninstall. Then try to install again.
System Restore

The ccleaner didn't pick up anything.
I can't go back before I uninstalled it because the restore was too old and dissapeared.

Hi, Benjiken. Welcome to Seven Forums.

MSE is one of the programs that requires .NET Framework to work. Unfortunately, there are times when .NET can be problematic. Since Error code 643 generally means that the update failed, let's start with the easy route with a Microsoft Fix it solution and see if that solves the problem.

Go to You receive error 0x80070643, error code 0x643 or updates may be re-offered when you try to install .NET Framework updates when using Windows Update or Microsoft Updates and scroll down the page to Method 1, Microsoft Fix it 50123. Follow the instructions there. If not requested to do so after running Microsoft Fix it 50123, restart your computer.

Following that, check that Windows updates. Install any .NET Framework updates separately from any other offered updates and restart the computer again.

Edit Note: If you receive error messages, please note carefully what they are and provide that information in your next reply.

I tried that and then I tried reinstalling .NET framework 3.5 with service pack 1 and .NET framework 4 client profile which were both installed before. So .NET 3.5.1 seemed to install ok but when I installed .NET 4 it crashed about halfway though with a "fatal error during installation.

I attached a summary of what the log said.

Darn! I just managed to lose the reply it took me some time to construct for you, Benjiken. Guess I need to start over. Solving .NET Framework issues can be a real hassle.

First, clean Temp Files. In order to be thorough, I suggest using the following tool:

Download TFC to your desktop

• Open the file and close any other windows.
• It will close all programs itself when run, make sure to let it run uninterrupted.
• Click the Start button to begin the process. The program should not take long to finish its job
• Once its finished it should reboot your machine, if not, do this yourself to ensure a complete clean

Next, download the standalone installer for .NET Framework 4.0 from Download Details - Microsoft Download Center - Microsoft .NET Framework 4 (Standalone Installer)

Right-click the downloaded installer and "Run as Administrator".

~~~~~~~~~~~~~~~~~~~~~~~~

If the above does not work, it is time to follow the suggestions provided by MSFT Aaron Stebner. Note that many of the linked articles have old dates. Aaron has updated them regularly though, including information for .NET Framework 4.

I suggest starting with the .NET Framework Setup Verification Tool User's Guide - Aaron Stebner's WebLog - Site Home - MSDN Blogs, using the command line switch: netfx_setupverifier.exe /q:a /c:"setupverifier.exe /a"

From there, if the Troubleshooting Guide doesn't help, see Updated: what to do if other .NET Framework setup troubleshooting steps do not help - Aaron Stebner's WebLog - Site Home - MSDN Blogs.

If you need to reinstall .NET Framework, see Mailbag: Should I re-install the versions of the .NET Framework in a specific order? - Aaron Stebner's WebLog - Site Home - MSDN Blogs.

Please let us know how you make out.

Where am I supposed to type in the command line switch: netfx_setupverifier.exe /q:a /c:"setupverifier.exe /a"

I tried it in the command line but it just said:

Hi, Benjiken.

You need to run the cmd prompt as Administrator. Click the start Orb and type cmd. When the search show cmd, right-click cmd and select "run as Administrator. Approve the UAC prompt.

My system works now!
This is how I did it.

I kind of gave up on fixing my system for a while then I tried what this tread said
windows installer service could not be accessed

It didn't work but then I decided to compare the registry key msiserver to the one on my netbook.

All I had to do to get installers such as Java or AVG anti-virus working again was to edit the "ImagePath" within msiserver.

I changed it from reading C:\Windows\SysWOW64\msiexec.exe /V to reading C:\Windows\System32\msiexec.exe /V

msi.exec.exe didn't exist in the sysWOW64 folder but it did in the System32 folder like my notebook.

Hi, Benjiken.

Thanks for getting back to us with your solution. I'll request the Moderators to mark your topic solved.