.NET throwing strange errors on PC start up

Question

Error message I get

I've been getting this error on my PC all of a sudden and I can't seem to fix it. I've tried running the .NET repair tool and it just doesn't work. It happens each time I boot up my PC and it pushes my CPU quite high.

Any suggestions on what could be causing it?

Extra details:

See the end of this message for details on invoking 
just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.Net.WebException: The remote server returned an error: (404) Not Found.
   at System.Net.WebClient.DownloadDataInternal(Uri address, WebRequest& request)
   at System.Net.WebClient.DownloadString(Uri address)
   at System.Net.WebClient.DownloadString(String address)
   at \]g0\&LF\*sX~\,Emin0(tar!}nf\*.‪‪‬‏‍‬‌‍‌‪‬‫‎‌‬‬‫‏‫‮‎‎‎‫‍‬‎‏‪‫‍‌‮(WebClient , String )
   at \]g0\&LF\*sX~\,Emin0(tar!}nf\*.‌‫‌‫‎‫‬‍‍‏‪‍‌‌‬‌‪‫‪‍‍​‮(Object , EventArgs )
   at System.Windows.Forms.Form.OnLoad(EventArgs e)
   at System.Windows.Forms.Form.OnCreateControl()
   at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
   at System.Windows.Forms.Control.CreateControl()
   at System.Windows.Forms.Control.WmShowWindow(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at System.Windows.Forms.Form.WmShowWindow(Message& m)
   at System.Windows.Forms.Form.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)


************** Loaded Assemblies **************
mscorlib
    Assembly Version: 4.0.0.0
    Win32 Version: 4.8.4300.0 built by: NET48REL1LAST_C
    CodeBase: file:///C:/Windows/Microsoft.NET/Framework/v4.0.30319/mscorlib.dll
----------------------------------------
CheckUpdate
    Assembly Version: 1.0.0.0
    Win32 Version: 13.9.0.0
    CodeBase: file:///C:/Users/Niishaw/AppData/Roaming/EventLog/CheckUpdate.exe
----------------------------------------
System.Windows.Forms
    Assembly Version: 4.0.0.0
    Win32 Version: 4.8.4270.0 built by: NET48REL1LAST_C
    CodeBase: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Windows.Forms/v4.0_4.0.0.0__b77a5c561934e089/System.Windows.Forms.dll
----------------------------------------
System
    Assembly Version: 4.0.0.0
    Win32 Version: 4.8.4300.0 built by: NET48REL1LAST_C
    CodeBase: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System/v4.0_4.0.0.0__b77a5c561934e089/System.dll
----------------------------------------
System.Drawing
    Assembly Version: 4.0.0.0
    Win32 Version: 4.8.4084.0 built by: NET48REL1
    CodeBase: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Drawing/v4.0_4.0.0.0__b03f5f7f11d50a3a/System.Drawing.dll
----------------------------------------
System.Configuration
    Assembly Version: 4.0.0.0
    Win32 Version: 4.8.4190.0 built by: NET48REL1LAST_B
    CodeBase: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Configuration/v4.0_4.0.0.0__b03f5f7f11d50a3a/System.Configuration.dll
----------------------------------------
System.Core
    Assembly Version: 4.0.0.0
    Win32 Version: 4.8.4320.0 built by: NET48REL1LAST_C
    CodeBase: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Core/v4.0_4.0.0.0__b77a5c561934e089/System.Core.dll
----------------------------------------
System.Xml
    Assembly Version: 4.0.0.0
    Win32 Version: 4.8.4084.0 built by: NET48REL1
    CodeBase: file:///C:/WINDOWS/Microsoft.Net/assembly/GAC_MSIL/System.Xml/v4.0_4.0.0.0__b77a5c561934e089/System.Xml.dll
----------------------------------------

************** JIT Debugging **************
To enable just-in-time (JIT) debugging, the .config file for this
application or computer (machine.config) must have the
jitDebugging value set in the system.windows.forms section.
The application must also be compiled with debugging
enabled.

For example:

<configuration>
    <system.windows.forms jitDebugging="true" />
</configuration>

When JIT debugging is enabled, any unhandled exception
will be sent to the JIT debugger registered on the computer
rather than be handled by this dialog box.

Answer 1

This is a generic exception dialog that appears under certain circumstances when software running on .NET encounters an error the developers did not account for. It is not a problem with .NET Framework itself.

Here, it's about receiving a HTTP 404 Not Found response. This may simply mean a remote resource was moved away/became unavailable.

The relevant information is visible (and can be copied) when you click the details button. It could help identify the program responsible. You should update your question with this information.

Further information is also visible in Event Viewer in the "Application" log.

---

From the information you added, we can see that the program in question is located at file:///C:/Users/Niishaw/AppData/Roaming/EventLog/CheckUpdate.exe.

Unfortunately, this means you’re most likely dealing with malware. Please read this Q/A on how to proceed from here: How can I remove malicious spyware, malware, adware, viruses, trojans or rootkits from my PC?