Windows 10: Windows Defender not opening/crashing

When I try to open windows defender, it keeps crashing. First I clicked the windows defender logo, and after that the logo shows up but crashes instantly. I tried restarting PC, nothing happened, trying to open it in Safe Mode, nothing happened. But I recently discovered that the Windows Defender is missing from the services.msc, I also tried, DSIM, SFC etc. but still its crashing. Please help I don't know how to bring back windows defender. I am not planning of resetting because I have important files and I have no backup. I have no system restore for older version so I cannot revert back.

:)

 

all games crash!

I suggest you run rthdribl > http://www.daionet.gr.jp/~masa/archives/rthdribl_1_2.zip
Increase the window size step by step and watch your vga temps permanently.
What happens?
If it crashes, run at stock speeds as suggested before and retry.

P.S.: When your system locks, does the display signal turn off after a time?
Stuttering sound or no sound at all when freezing?
What X1800XT model do you own exactly?

 

Windows Defender Security Centre crashes on opening

Every time I try to open Windows Defender Security Centre, the window opens and closes immediately. There is no error logged in the event logs.

The old Windows Defender interface - MSASCui.exe opens just fine; the problem lies with MSASCuiL.exe which crashes instantly after opening.

I do not have any other antivirus software installed, nor have I ever. Scans with Microsoft Safety Scanner and MSASCui.exe do not find any malware.

Steps tried

1. All the steps listed here on the troubleshooting article.

2. sfc /scannow reveals no problems

3. dism /online /cleanup-image /restorehealth completes successfully but to no avail

4. Clean boot performed

5. In-place install performed

6. Attempted to open in safe mode

None of the steps above seem to work.

I am using a desktop I built myself, running windows 10 v1703 build 15063.632. The Defender Security Centre has worked in the past but for some strange reason has not for the past week, or so I noticed.

Please do assist - a clean fresh install is however not an acceptable solution as this is a critical work computer.

 

all games crash!

ive watch my temps and both the cpu and gpu are within normal ranges. when it freezes it simply freezes the image and stops the sound. i must reboot to get back to windows.