HDMI input feed on the AIO Inspiron 7720

Version of Windows?

Are batteries fresh in the wireless mouse?

A lot of static electricity on/around the screen?

Are BIOS and drivers up-to-date for your version of Windows?

Have you tried using a different USB mouse with its own USB dongle or tried a wired USB mouse?

@RoHe  Thank you for your response and suggestions.

I forgot to mention in my original post that this is my second Inspiron AIO so the AIO Inspiron 7720 is just replacing the old. 

I used the old Inspiron AIO as an extended monitor exactly in the same way that i am using the new AIO ie same wireless keyboard, mouse etc. The only difference is that I am using a new Inspiron AIO. I had no issues using  the old Inspiron AIO as an extended monitor.

Answers to your questions :-

• Version of Windows?
  Windows 11 Home 10.0.26100
  
  
• Are batteries fresh in the wireless mouse?
  Yes
  
  
• A lot of static electricity on/around the screen?
  No
• Are BIOS and drivers up-to-date for your version of Windows?
  Yes
  
  
• Have you tried using a different USB mouse with its own USB dongle or tried a wired USB mouse?
  I tried this approach today and unfortunately has made no difference.

@RoHe Just curious, have used, or using Inspiron AIO,  as an extended monitor ?

Was the other mouse that you tried wireless or wired?

Open Windows Event Viewer and see what/any errors might be listed at the time it switches from using HDMI-in and starts using its own display.

A bum source selection button on the AIO?

Is it possible the fault is at the other end? In other words, the Mac or laptop stop sending the HDMI signal to the AIO, so it reverts to using its internal monitor? Have you tried a different HDMI cable from PC's HDMI-out to AIO's HDMI-in?

It's unfortunate you didn't set this AIO up right away and now your warranty has expired. If you bought this PC with a credit card, check with that card to see if they offer any free warranty extensions. Some cards may give a second year of coverage within first year after original warranty expired, as long as your cost to repair or replace the item is charged on that same card.  And then use Dell Out-Of-Warranty service.

Otherwise, I guess you could buy an extended warranty from Dell that -hopefully -will cover this issue. 

Don't own or use an AIO, so no first-hand experience using one as an extended monitor....

@RoHe Sorry for the late response.

This issue is encountered with both a wired and wireless mouse.

Open Windows Event Viewer - I didn't see anything obvious but again not sure what I was looking for either so could be lack of understanding on my side here.

Is it possible the fault is at the other end? - quite possible. 

I am going to look to see if there is any pattern when this issue is encountered. As mentioned, one definite scenario I know when switch over occurs is when mouse is moved/buttons selected. 

As I am not a technical person, I did take out a 4 year premium cover. I have already raised this issue with Dell. They have performed a remote session on to the computer, made some config change but issue is still there. I have to get back to them.

So the purpose of this thread was really to ascertain if there other people who may be experiencing same issue. @RoHe you have already mentioned that you don't use this setup.

If I get any useful updates on this issue, will update this thread.

Pankaj

Are there any Critical errors or Warnings listed in Event Viewer around the time of the switchover?

Are these mouse clicks on the mouse connected to the AIO or to the other system?

Have you tried a different HDMI cable?

You can try this on the AIO:

1. At desktop, open a CMD prompt window, Run as administrator
2. At the prompt, type in: DISM.exe /Online /Cleanup-image /Restorehealth and press Enter. Be sure to include a space in front of each / and note any error messages when that's done.
3. Assuming no "unfixed issues" in #2, at the CMD prompt, type in: sfc /scannow and press Enter. Be sure to include a space in front of the / and note any errors when that's done.
4. Assuming no "unfixed issues" in #2 or #3, reboot and test HDMI-in again...

Definitely follow up with tech support. They may need you to send the PC in for testing/repairs. 

FWIW, I searched these forums but didn't find any similar HDMI issues about the Inspiron 7720....