The “Unknown Hard” error that keeps on appearing in Windows 10 can put users in an unpleasant situation. This kind of error leads to the freezing of the taskbar, blackening of the screen, and sudden disappearance of the icons on the Desktop. And each time you try to open Windows, the system will only give you an error message saying that it’s a critical error and some applications like Start and Cortana won’t work.
Upon analysis, it seems that the “sihost.exe” is not responding and that it is the one that’s causing the c000021a Unknown Hard error to pop up. Sihost.exe files represent the Shell Infrastructure Host which is an essential component in the Windows operating system. The Windows Shell Infrastructure Host is primarily responsible for handling some graphical elements of the operating system interface such as the Start menu and the taskbar transparency. And so if the Shell Infrastructure or Sihost.exe has stopped, has been removed, or corrupted, you will most likely have issues with the overall functionality of the Windows operating system and you’ll get the Unknown Hard error
In addition, the ctfmom.exe Unknown Hard error may also occur due to incompatible drivers installed on your PC. Ctfmom is a process that identifies inputs such as handwriting, languages, and many more. It’s the one that controls the functions of background behavior. To resolve this issue, you need to first try to identify which application is the one that’s running the sihost.exe file. And if needed, you need to either update or reinstall or completely uninstall the problematic application.
The SFC Scan or System File Checker, us a built-in utility in Microsoft Windows that can be found in the C:\Windows\System32 folder. This tool allows users to scan and restore any corrupted system files in Windows that might be causing the Unknown Hard error to appear. Before you use this tool, make sure to find out whether the sihost.exe on your computer is a Trojan that you have to remove or if it’s a file that belongs to a trusted Windows application. Once you have that sorted out, follow the steps below.
The command will start a system scan which will take a few whiles before it finishes. Once it’s done, you could get the following results:
You can also try using System Restore. This is one of the ways you can use it to back up your PC. Since restore points are created automatically each week by System Restore, you can use System Restore to restore your computer back to an earlier good point in time.
Putting your PC in a Clean Boot state can help you diagnose and troubleshoot the issues in your system. During this state, you can start the system with a minimum number of drivers and startup programs that will surely help you in isolating the root cause of the Unknown Hard Error.
After putting your PC in a Clean Boot State, try creating a system restore point and see if the problem still occurs. Clean Boot troubleshooting is designed to help you isolate the problem. For you to execute a clean boot troubleshooting, you must do a couple of actions (the steps are given above) and then restart your PC after every action. You might have to disable one third-party app after the other to really isolate the issue. And once you’ve narrowed down the problem, you can either disable the third-party app that’s causing the problem or remove it. Note that you must switch your PC back into the Normal Startup mode after you’re done troubleshooting the problem. Here’s how you can do it:

Microsoft has not published a solution to this issue, but users point out two potential problems. The first is a security mechanism based on disk virtualization, which is supposed to slow down the performance of SSDs.
The second, in turn, is related to the place of installation of Windows 11 – users indicate that if the performance test is performed on a medium with no files associated with the system, its performance results are similar to the parameters given by the manufacturer.
Transfer speeds were to be slightly improved with the latest Windows 11 update 22000.348. However, users are still waiting for a solution to the problem that significantly reduces the efficiency of SSD media.
Enter Cooler Master XG850 PLUS PLATINUM, a new, in-house designed power supply from Cooler Master. I will admit that in last years I was a big fan of Cooler Master and their components, well not all but power supply and PC cases were always products from them that I liked and used. The latest power supply from them does not disappoint and I must say that I like it very much, it is hi-quality, it is silent, it has a large LCD display where you can see its current state and also has some RGB lights so it looks cool in your case.

So without further detours here are the technical specifications and then we will talk a little about it.
| Model: MPG-8501-AFBAP-X |
| ATX Version: Intel ATX 12V Ver. 2.53 |
| PFC: Active PFC |
| Input Voltage: 100-240V |
| Input Current: 12-6A |
| Input Frequency: 50-60Hz |
| Dimensions (L x W x H): 160 x 150 x 86 mm |
| Fan Size: 135mm |
| Fan Speed: 1800 RPM |
| Noise Level @ 100%: ≤ 25 dBA |
| Efficiency: ≥ 92% @ Typical Load |
| 80 PLUS Rating: 80 PLUS Platinum |
| ErP 2014 Lot 3: Yes |
| Operating Temperature: 0-50°C |
| Power Good Signal: 100 - 150 ms |
| Hold Up Time: ≥ 16ms |
| MTBF: >100,000 Hours |
| Protections: OPP, OVP, OCP, UVP, SCP, OTP, Surge, and Inrush Protection |
| Regulatory: TUV, cTUVus, CE, BSMI, FCC, CCC, EAC, UKCA |
| ATX 24 Pin Connectors: 1 |
| EPS 4+4 Pin Connectors: 1 |
| EPS 8 Pin Connector: 1 |
| SATA Connectors: 12 |
| Peripheral 4 Pin Connectors: 4 |
| PCI-e 6+2 Pin Connectors: 6 |
| USB Protocol 10P: 1 |
| Series: XG Series |
| 80 Plus: Platinum |
| Modular: Full Modular |
| Wattage: Above 750W |
If we put aside the technical characteristics of the power supply itself we are left with visual and real working experience. Now real working experience will not be covered here since yea it is working great but it needs some time and a long period of testing in order to be able to say that it is indeed reliable and great but considering I have never had any issues personally with power supplies from Cooler Master I will assume that this one is also very reliable and hi-quality.
That leaves us basically with looks and feels of supply itself and I must say that I like it, and I mean I like it a lot. It feels hi-quality and it looks hi-quality. The LCD display is very good looking and it is very crisp and readable. With power supply some proprietary software so you can choose what you want on display on the screen and also you can control RGB and display colors with it.
I have not opened the power supply to see how it looks inside but from what I could see I think this would be my new power supply if I were building a new PC now. I recommend it and if you decide to get it I hope it will serve you long long time.
Thank you for reading and I hope to see you next time.
Error Causes
Error Causes“This application has failed to start to run on Windows because MSASCUI.exe cannot be found.” “Windows Defender cannot work properly and protect the Windows system effectively”The message will keep popping up on your computer screen time and again.