Antimalware Defender is not legit security tool. The software is a rogue antispyware program. The rogue is distributed and installed through the use of trojans that masquerade as Security Windows Critical Update. When the trojan is started, it will display a screen that stats:
Antimalware security update for Windows XP (KB961118)
Size: 433KB
This critical update will install System Security Update 2010.01.023 (Antimalware Defender Upgrade; KB648759)
Then it will download and install Antimalware Defender onto you computer and configure it to run automatically when Windows starts.
Once Antimalware Defender is started, it will simulate a system scan. Once finished, the rogue will list legitimate Windows files and not existing files as infections that will not be fixed unless you first purchase the program. Important to know, all of these reported infections are fake, so you can safely ignore the scan results that Antimalware Defender gives you.
As you can see, Antimalware Defender is a scam and should be removed from the system upon detection. Do not be fooled into buying the program. Instead of doing so, follow the removal guide below in order to remove Antimalware Defender and any associated malware from your computer for free.
Use the following instructions to remove Antimalware Defender (Uninstall instructions)
Download MalwareBytes Anti-malware (MBAM). Once downloaded, close all programs and windows on your computer.
Double-click on the icon on your desktop named mbam-setup.exe. This will start the installation of MalwareBytes Anti-malware onto your computer. When the installation begins, keep following the prompts in order to continue with the installation process. Do not make any changes to default settings and when the program has finished installing, make sure a checkmark is placed next to “Update Malwarebytes’ Anti-Malware” and Launch “Malwarebytes’ Anti-Malware”. Then click Finish.
MalwareBytes Anti-malware will now automatically start and you will see a message stating that you should update the program before performing a scan. If an update is found, it will download and install the latest version.
As MalwareBytes Anti-malware will automatically update itself after the install, you can press the OK button to close that box and you will now be at the main menu. You will see window similar to the one below.

Malwarebytes Anti-Malware Window
Make sure the “Perform quick scan” option is selected and then click on the Scan button to start scanning your computer for Antimalware Defender infection. This procedure can take some time, so please be patient.
When the scan is finished a message box will appear that it has completed scanning successfully. Click OK. Now click “Show Results”. You will see a list of infected items similar as shown below.
Note: list of infected items may be different than what is shown in the image below.

Malwarebytes Anti-malware, list of infected items
Make sure all entries have a checkmark at their far left and click “Remove Selected” button to remove Antimalware Defender. MalwareBytes Anti-malware will now remove all of associated Antimalware Defender files and registry keys and add them to the programs’ quarantine. When MalwareBytes Anti-malware has finished removing the infection, a log will open in Notepad and you may be prompted to Restart.
Note: if you need help with the instructions, then post your questions in our Spyware Removal forum.
Antimalware Defender creates the following files and folders
c:\Program Files\Antimalware Defender
c:\Program Files\Antimalware Defender\Antimalware Defender.dll
c:\Documents and Settings\All Users\Start Menu\Programs\Antimalware Defender
c:\Documents and Settings\All Users\Start Menu\Programs\Antimalware Defender\Antimalware Defender.lnk
%UserProfile%\Application Data\Microsoft\Internet Explorer\Quick Launch\Antimalware Defender.lnk
%UserProfile%\Desktop\Antimalware Defender.lnk
%UserProfile%\Start Menu\Programs\Antimalware Defender
%UserProfile%\Start Menu\Programs\Antimalware Defender\Antimalware Defender.lnk
Antimalware Defender creates the following registry keys and values
HKEY_CLASSES_ROOT\CLSID\{ca84c702-c758-4421-974e-b02662e76d7c}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\{ca84c702-c758-4421-974e-b02662e76d7c}
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run | ca84c702-c758-4421-974e-b02662e76d7c_6
Oh Man! Thanks a lot for an advice! You’ve saved my life:D