Microsoft Security Essentials install problem

I'm not sure what happened, but MSE disappeared from my programs list, so I tried to re install it, but I get an error: 0x80070643
I'm freaking out

And I'm sorry if this is in the wrong area.

First try a system restore to a point before the disappearance of MSI.

If necessary, try to uninstall MSI using Revo Uninstaller Pro, and then re-install it. If you don’t want to buy Revo, you can use it on free trial.
http://www.revouninstaller.com/

If still no success, consider the following:
This error may occur if the MSI software update registration has become corrupted, or if the .NET installation on the computer has become corrupted.

To troubleshoot this issue, try to repair the MSI software update registration corruption issues. If that doesn't work, try to repair the .NET Framework.

For the (easy) procedures for doing the above see:
http://support.microsoft.com/kb/976982

I'm not sure how to do a system restore.
It doesn't show up on Revo.
I've tried the last thing, but it didn't work.

Edit: I tried to do a system restore with whatever the computer comes with, but it said my hard disk is corrupted. I got an option to check for errors, but apparently I can't do that while it's in use, so I clicked the option that says schedule for a check upon start up. So I restarted my computer but nothing happened.

Also, what should I do about having no MSE? Get another thing?

What browser are you using & your Operating System?

This problem occured on my sisters PC. Are you getting this error through Windows Update? If so download it from here as a stand alone: http://windows.microsoft.com/en-US/windows/security-essentials-download <--This fixed my issue.

Other free AV programs do have dedicated "remover" programs.

However, in Windows 7, you just follow this file path to do a system restore: Start Button >Control Panel > "Recovery", then follow the instructions.

BTW, sometimes when an AV program fails to update, or disappears, there is always the possibly the problem may have been caused by malware. Jus' sayin', keep an open mind.

Also, mse may be gone from system tray as soon as the latest mse february 2013 update is being installed.
after the mse update, mse will be seen again.

if the above scenario does not apply in your case, from add/remove programs (xp/vista or "Control Panel\Programs\Programs and Features" for 7) uninstall mse, then just re-download/re-install mse from:
http://windows.microsoft.com/en-US/windows/security-essentials-download

I had to restart my PC after installing so it functioned properly

I don't really know what went wrong and when.
This is a school laptop, so I'm going ask them to replace my hard disk.
Thanks for the input, all.

I asked you which browser because in the browsers I've used, you can select where the downloads go to.
Usually the desktop. By default, I believe most/all browsers download to a "downloads" folder.

I use firefox and I always choose the download location. I have Windows 7 64 bit.
The error message comes from installing it as a stand alone.
I can't do a system restore b/c I get an error that states the disk has errors. And when I schedule a disk scan, it doesn't do one.
MSE doesn't show up in Add/Remove Programs. It seems gone.

I got this error when doing a restore before. I resolved it by running the restore again.

I'd advice you to use other free Antivirus as MSE is dropped down the list.

I find MSE to be fine despite failing those tests... give it time. It is so minimalistic and does its job with the worst viruses (been using it since day 1) and haven't had any issues while people using Avast and AVG have some issues that I do not have.

I used MSE for about a half year. I know what it can do. If you're a normal user, no need to change but If you're more like a hacker/cracker or developer you would know MSE has lower detection, and definitively not a recommendation.

To fix this issue uninstalled MSE use CCleaner on registry. Then reboot then install the new pre-release version 9/12 or the most current 9/12. These will work. I had this issue myself on two systems. Tried every cleaner and none could find the issue was in the registry.