To resolve this issue, uninstall Microsoft Security Essentials, delete any remaining registry subkeys, and then manually install the latest version of Microsoft Security Essentials.
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Note: Before you uninstall Microsoft Security Essentials, make sure that Windows Firewall is turned on. Antivirus software helps protect your computer from viruses. You must not download or open files from sources that you do not trust, visit websites that you do not trust, or open email attachments when your antivirus software is disabled. For more information about computer viruses, see the following article in the Microsoft Knowledge Base:129972: How to prevent and remove viruses and other malware
To do this, follow these steps.
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Note: You may find it easier to follow the steps if you print this article first.
Click Start, click Run, type or copy and paste appwiz.cpl in the Run box, and then click OK.
Select Microsoft Security Essentials, and then click Uninstall.
Restart the computer.
Windows Vista or Windows 7
Click Start, type or copy and paste Appwiz.cpl in the Search box, and then press Enter.
Right-click Microsoft Security Essentials, and then click Uninstall.
Restart the computer.
If you were able to uninstall Microsoft Security Essentials by using the previous steps, go to Step 4: Reinstall Microsoft Security Essentials. If you were unable to uninstall Microsoft Security Essentials, and some Microsoft Security Essentials components may not be uninstalled, you may be unable to reinstall Microsoft Security Essentials.
If you cannot uninstall Microsoft Security Essentials by using Add or Remove Programs or the Programs and Features item, Step 2: Back up the registry and Step 3: Delete registry subkeys for Microsoft Security Essentials.
Important This section, method, or task contains steps that tell you how to change the registry. However, serious problems might occur if you change the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you change it. Then, you can restore the registry if a problem occurs.
For more information about how to back up and restore the registry, see the following articles in the Microsoft Knowledge Base or Windows Help and How to:
To have us delete registry subkeys for Microsoft Security Essentials automatically, click the Fix it button or link. Click Run in the File Download dialog box, and then follow the steps in the Fix it wizard.
If you prefer to fix this problem yourself, go to the "Let me fix it myself" section.
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Notes
This wizard may be in English only. However, the automatic fix also works for other language versions of Windows.
If you are not on the computer that has the problem, save the Fix it solution to a flash drive or a CD and then run it on the computer that has the problem.
Let me fix it myself
Stop the Microsoft Security Essentials Process:
Open Task Manager. To do this, follow the steps for the operating system that you are running:
For Windows XP
Click Start, click Run, type or copy and paste taskmgr in the Run box, and then click OK.
For Windows 7 and for Windows Vista
Click Start, type or copy and paste taskmgr in the Search box, and then click taskmgr.exe.
Click the Process tab.
Find the msseces.exe file entry. Right-click the entry, and then click End Process. If a confirmation window appears, click End Process.
Stop and disable the Microsoft Security Essentials service:
Windows XP
In Windows XP, click Start, and then click Run.
Type or copy and paste net stop msmpsvc, and then click OK.
Click Start, and then click Run.
Type or copy and paste sc config msmpsvc start= disabled, and then click OK.
Windows Vista or Windows 7
In Windows Vista or Windows 7, click Start, type run in the Search box, and then click Run.
Type or copy and paste net stop msmpsvc, and then click OK.
Click Start, type run in the Search box, and then click Run.
Type or copy and paste sc config msmpsvc start= disabled, and then click OK.
Delete the Microsoft Security Essentials run subkey:
Windows XP
In Windows XP, click Start, and then click Run.
Type or copy and paste regedit, and then click OK. If a User Account Control window appears, click OK.
Click the following subkey: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
In the details pane, click Microsoft Security Essentials, and then click Delete.
Windows Vista or Windows 7
In Windows Vista or Windows 7, click Start, type run in the Search box, and then click Run.
Type or copy and paste regedit, and then click OK. If a User Account Control window appears, click OK.
Click the following subkey: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
In the details pane, click Microsoft Security Essentials, and then click Delete.
Delete the remaining MSE registry subkeys:
Windows XP
Click Start, and then click Run.
Type or copy and paste regedit, and then click OK. If a User Account Control window appears, click OK.
In the details pane, click Microsoft Security Essentials, and then click Delete.
Under the alphanumeric keys, search for the following entries, right-click each entry, and then click Delete:
Microsoft Antimalware Service XX-XX Language Pack, where XX-XX is the installed locale id. Each language locale has its own id. Delete all subkeys that are in this format, regardless of the locale id. This subkey is not present for U.S. English (en-us) installations.
In the details pane, click Microsoft Antimalware, and then click Delete.
Windows Vista or Windows 7
Click Start, type run in the Search box, and then click Run.
Type or copy and paste regedit, and then click OK. If a User Account Control window appears, click OK.
Click the following subkey: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Current version\Uninstall\Microsoft Security Client
In the details pane, click Microsoft Security Essentials, and then click Delete.
Under the alphanumeric keys, search for the following entries, right-click each entry, and then click Delete:
Microsoft Antimalware Service XX-XX Language Pack, where XX-XX is the installed locale id. Each language locale has its own id. Delete all subkeys that are in this format, regardless of the locale id. This subkey is not present for U.S. English (en-us) installations.
Microsoft Antimalware
Microsoft Security Client
Click the following subkey: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft Security Client
In the details pane, right-click Microsoft Security Client, and then click Delete.
Click the following subkey: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft Antimalware
In the details pane, click Microsoft Antimalware, and then click Delete.
Delete installer subkeys:
Windows XP
Click Start, and then click Run.
Type or copy and paste regedit, and then click OK. If a User Account Control window appears, click OK.
Locate the following subkey: HKEY_CLASSES_ROOT\Installer\Products
Under the alphanumeric keys in the ProductName field, search for the following entries. Note the numbers for each instance that you find. Right-click each entry, and then click Delete:
Microsoft Security Client
Microsoft Antimalware
Microsoft Antimalware Service XX-XX Language Pack, where XX-XX is the installed locale id. Each language locale has its own id. Delete all subkeys that are in this format, regardless of the locale id. This subkey is not present for U.S. English (en-us) installations.
Windows Vista or Windows 7
Click Start, type run in the Search box, and then click Run.
Type or copy and paste regedit, and then click OK. If a User Account Control window appears, click OK.
Locate the following subkey: HKEY_CLASSES_ROOT\Installer\Products
Under the alphanumeric keys in the ProductName field, search for the following entries. Note the numbers for each instance that you find. Right-click each entry, and then click Delete:
Microsoft Security Client
Microsoft Antimalware
Microsoft Antimalware Service XX-XX Language Pack, where XX-XX is the installed locale id. Each language locale has its own id. Delete all subkeys that are in this format, regardless of the locale id. This subkey is not present for U.S. English (en-us) installations.
Select the appropriate language and operating system, and then click Download.
Click Run, and then follow the instructions to complete the installation.
Restart the computer.
Did this fix the problem?
If you were able to install Microsoft Security Essentials, the problem is fixed and you are finished with this section. If the problem is not fixed, you can contactMicrosoft Support.
We would appreciate your feedback. To provide feedback or to report any issues with this solution, please leave a comment on the "Fix it for me" blog or send us an email message
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