Cast (to a wireless display) Pops Up Repeatedly (without any request)

Okay, this is truly bizarre. I've rebuilt an HP deskto PC that had Windows 11 and was wiped clean, reformatted, and reinstalled. That was a few weeks ago.

Suddenly, the Cast pop-up window appeared without any invitation and won't go away. At times the pop-up takes over the Active window there is no control in any other window, so much that only a hard-shutdown will stop it. But after a reboot, the Cast will pop back up, regardless.

I have no idea why it keeps coming up or how to stop it.

HELP!!!

In the Search box,type in---dxdiag--- and look in the Display page to see if Miracast is mentioned.
If it is,then uninstall it,power off shutdown then restart.
Forgot to mention that whilst in dxdiag,check the other pages for comments.
If the problem no longer shows,then reinstall Miracast from the Microsoft store.

You said you rebuilt this PC.

1. Ensure there is no grounding issues
2. Double check the connected keyboard
3. You accidentally press WIN+K. while using the KB.

This popup should not appear by itself, and because it sounds like it locks you out of everything, I suspect a deeper issue with either your hardware or Windows itself...

I don't have 11, but if I am not mistaken your screenshot shows the Windows Key + K as the trigger, This seems to indicate the keyboard sent that request, or the PC thinks it did. Unplug the keyboard and see if it goes away. You can disable the shortcut too, I asked AI as again I do not have 11

Disable the Windows + K Shortcut Entirely
If you cannot replace the keyboard right away, you can use a free, official Microsoft tool to completely disable that specific keyboard shortcut so it can no longer trigger the pop-up. Download and install Microsoft PowerToys (available safely from the Microsoft Store). Open PowerToys and click on Keyboard Manager on the left menu. Make sure "Enable Keyboard Manager" is turned On. Click Remap a shortcut. Click the + (Add shortcut remapping) button. Under "Select:", press or input Win + K. Under "To:", click the dropdown menu and change it to Disable. Click OK at the top right to save.

Someone will correct me if the process is different

A Guy