I recently tried to run Windows Defender. It gave me this error. I navigated to the windows folder and tried to run it directly. Even though I clicked on the exe file it still wouldn't load giving me the error "Windows cannot find 'C:\Program Files\Windows Defender\MSASCUI.exe'. Make sure you typed the name correctly, and then try again." I am not running any antivirus other than this one and this is a relatively new reinstall of windows 8.1 Pro.

i suggest you scan your PC using malwarebytes, I suspected there is malware inside your PC

if doesn't work try system file checker or system restore (using restore point)

• Edited by britishdhez 4 hours 25 minutes ago

i suggest you scan your PC using malwarebytes, I suspected there is malware inside your PC

if doesn't work try system file checker or system restore (using restore point)

• Edited by britishdhez Tuesday, June 02, 2015 2:56 AM

Hi,

Agree with last post, the system file checker (commands: SFC /SCANNOW) can help to repair the file related to Windows defender.

• MSASCui.exe is the Defenders User Interface application situated in C:\Program Files\Windows Defender folder.
• MpRtMon.dll is Defenders Realtime Monitor dll, situated in C:\Program files\Windows Defenderfolder.

If it didn't work, try manually replace the files above. However its copies can also be found in the following folder/s :

C:\windows\winsxs\x86_security-malware-windows-defender_31bf3856ad364e35_6.0.6000.16386_none_5585eece5b4407f1

C:\windows\winsxs\x86_security-malware-windows-defender_31bf3856ad364e35_6.0.6000.16420_none_55c0ce805b18c568

C:\windows\winsxs\x86_security-malware-windows-defender_31bf3856ad364e35_6.0.6000.20516_none_565b3cf37428e14b

You will have to unhide hidden files and show system files from the Folder Options, to be able to see them.

The last numerals may differ, but essentially these are the folders. The winsxs folder is the native assembly cache. Libraries which are shared by multiple programs are stored there. You may also find different versions of the same dll files in these folders. Login as Administrator and try to replace the dll in the /Windows Defender/ folder with one of these dlls. Reboot and see if it helps.