Unable To Install Microsoft Security Essentials <Solved>

I’ve just spent the past hour or so fighting a co-worker’s personal computer, trying to get Microsoft Security Essentials to re-install (she had originally installed v1 of MSE, and when the v2 came out not too long ago and it attempted to upgrade, apparently it hosed her antivirus installation).  Her machine is running XP SP3 32-bit.

The original error code we received was 0x80070002 when trying to run the v2 installer.  I tried to run the v1 installer (downloaded from FileHippo.com), hoping to re-write whatever had become corrupted (as Add/Remove Programs didn’t show MSE as being installed at all).  However, that didn’t do anything, and it ended up failing to install as well.  From there, I went into Program Files and renamed the Microsoft Security Essentials folder so that the installation would be able to write to a fresh folder.  That didn’t work.  Then, I entered the Registry…

In the Registry, I searched for “Security Essentials” and proceeded to delete every KEY (which is the term for the folders) that contained any items referencing Security Essentials.  This took a while.  I re-ran the installation after that, to no avail.

I then went digging around the Application Data folder (C:\Documents and Settings\All Users\Application Data) and deleted the Microsoft Security Essentials folder and files.  I also went back into the Registry and searched for “Microsoft Antimalware” and again deleted every key containing items referencing the string I searched for.

At one point, after ripping enough items out of the registry, the error message I received changed.  It eventually  became 0x80070643, 0x80070648 and finally 0x80070645.  I then found a post that described two registry keys that could be causing problems (they appear to be telling the installer to upgrade rather than do a fresh install).  Once I removed these two keys and rebooted, all was well after re-attempting to install.  Below are the two keys I removed.

HKEY_CLASSES_ROOT > Installer > UpgradeCodes > 1F69ACF0D1CF2B7418F292F0E05EC20B

—Right click on1F69ACF0D1CF2B7418F292F0E05EC20B and delete the key

HKEY_LOCAL_MACHINE > SOFTWARE > Microsoft > Windows > CurrentVersion > Installer > UpgradeCodes > 1F69ACF0D1CF2B7418F292F0E05EC20B

— Right click on1F69ACF0D1CF2B7418F292F0E05EC20B and delete the key.

I’m not sure if everything I did is necessary in order to achieve the desired results.  I’d recommend trying to remove the two last keys mentioned first, and if that doesn’t work, do everything else.  As always, keep in mind, removing information from the Registry is potentially dangerous to your system’s health, so make a backup of the Registry before proceeding.