CAS Crashing in Windowed Mode on PC after switching to another window

hashtag-anthems​  Please provide a dxdiag.  Click Windows key-R, enter dxdiag in the run box, wait for the scan to finish, click "Save all information," and save the file to your desktop.  From there, you can attach it to a reply using the paper clip (Attachment) icon included with the other formatting buttons.

Please also let me know whether this happens if you put the EA App in offline mode before launching Sims 4.  If it doesn't help, do the same but take your computer offline entirely.  I realize you wouldn't want to play like that since you're used to having access to other apps, but it's a test rather than a fix.

Okay, I have the dxdiag attached to this reply, I hope. 

I put the EA app into offline mode with my laptop still connected to WiFi before launching Sims 4, and it crashed even sooner. Before, it was consistently one minute after switching windows, but this time it was almost immediately after I switched windows to Firefox where I have this topic open.

After disconnecting my laptop from the internet entirely and having the EA app in offline mode, I switched to Firefox and let the game sit running in the background for six minutes, and it didn't crash. I turned WiFi back on at that point, went back into the game to exit out of it, and it was unresponsive, crashed, and relaunched. Normally with this problem, it doesn't automatically relaunch. 

hashtag-anthems​  Your dxdiag lists a number of BlueScreens.  It doesn't sound like you're seeing these while playing Sims 4, but what is the context?  The problem here, from the perspective of the Sims 4 crashes, is that these BSODs have crowded out almost everything else in the dxdiag.

For the Sims 4 crashes, try clearing temp files.  Click Windows key-R and enter %temp% in the run box, which should bring you to a Temp folder.  Delete everything inside and restart your computer.  If you can't delete some files, restart and try again, then restart afterwards too.

Honestly, I wish there was a single context for this stupid laptop crashing. I got it in April, it has good hardware, it was brand new sealed in the box, I had the RAM upgraded but I'm like 99.9% sure that's not the issue because by all accounts it seems to be installed correctly and it's confirmed compatible with my machine from the manufacturer. This laptop has just been crashing periodically since I started using it, and there's no one specific stop code, I've gotten multiple that I should honestly be keeping track of, but when I look them up on Microsoft's website, the help threads always seem to be related to things I'm not even doing. I miss my Windows 10 laptop every day. 😭

I'm not usually bad with computers, I've just been busy coping with multiple family illnesses/one death in the family, work problems, and trying to sell a house, so deciphering the BSODs has been near the bottom of my list of priorities. I just live like this right now. I've been using Windows computers since Windows 98 and I've always been able to wrestle them into submission, but taming Windows 11 is proving to be beyond my current emotional bandwidth. 😔

I tried clearing temp files, there were a couple I couldn't clear because they were in use in the NVIDIA app, I closed the NVIDIA app, then it said it couldn't clear them because they were no longer located in that folder (so, successfully cleared out?) and then there were a couple that just would. not. delete. So I restarted like you said, tried to clear it out again, and there were still a couple that wouldn't delete because they were in use in Microsoft Edge WebView2? I can't even find that in my Task Manager to kill it, and I know it's a separate program from Microsoft Edge (which still tries to launch even though I have startup launch disabled)? I tried restarting again and launching Sims 4 anyway (internet enabled) because it did clear out a majority of the files, and then Sims 4 crashed as it has been when I'm in another window, but this time it gave me this pop-up which it normally doesn't: 

When I clicked Restart App, it restarted the EA app and not Sims 4. 

hashtag-anthems​  The error message you've posted is from the EA App itself, so it's unsurprising that it would restart the App and not the game.

You should be able to disable any Edge-related services through msconfig .  This would also stop them from opening when you launched Edge, unless you undid the change, but it's easy to apply either way once you've found the location of the problem service on the list.

A temporary workaround is of course to take your computer offline when you're using CAS, and only then.  I realize it's not ideal, but you could download Gallery sims at other times, then choose to load a sim from your library when you wanted somewhere to start in CAS.

For the BlueScreens, something to consider is reinstalling Windows.  While you could, if you had the time and the mental energy, try to troubleshoot each one, when there are several different kinds of errors that aren't necessarily all of the same type, it's often easier, not to mention faster, to start fresh.  I'm not suggesting you have to, and certainly not right now; this is just something to keep in mind.

The other detail to keep in mind is that a RAM issue can look like almost anything else.  So I would also suggest removing and re-seating your modules, and if that doesn't help, reinstalling the original sticks instead.  Even if it's not a long-term solution for your use case, it's a helpful test.

I will be here whenever you're ready to troubleshoot, with whatever approach you want to try first.  I've seen what this kind of situation does to someone and completely understand if you need to put the issue on ice for now, then come back at some uncertain point in the future.