Very interesting thread here.
One thing I agree with here is to get rid of the Bullguard AV; which I am not familiar with and I've done a lot of work with AVs since 1980 and beta test many of the well know products. I'm not familiar with these guys, and that doesn't mean they are bad, just that they don't show up on any of the independent AV testing companies' annual Best AV products reviews. period. That's not a good sign, as no one reliable has tested that product.
When new AV companies launch products they usually attempt to get reviewed in e-zines that are computer related such as PC World, PC Magazine, CNET, etc. They also attempt to get in the door in the corporate business world. To my knowledge this product has not been adopted by any of the Fortune500 companies; and I'm pretty familiar with all the products they run. Another bad sign IMO.
You might also consider that we see a lot of these so-called fantastic AV products that get shipped with new computers (mostly laptops) by the manufacturer since the manufacturer gets paid by the AV company to include their product free or trialware with their computers to the public to get it out there so to speak. In my experience, these products are not yet mature, they misbehave frequently, and can do serious damage to your laptop including damaging the hardware as you suspect. They also contain much spyware, which often is a lowly collusion between the AV maker, the computer manufacturer, and questionable marketing companies on the Internet *which abound you know*.
Speaking only for myself, I
NEVER use or recommend any AV products unless I have thoroughly tested them out on my own personal home network and computers, and then slowly deploy them into my Business customer's being very careful there, as you can imagine if you pick a product that scrambles even 1 computer or their entire network of hundreds or thousands of computers, you certainly will not ever be asked back, not to mention possible litigation from the Customer for their downtime, cost of lost sales revenue, etc. etc.
You got some good advice from some of the Team here about doing an in-place upgrade repair or a Windows reset, and then just running only Windows Defender, which a lot of the guys run here and swear by; but it doesn't protect me or my Customers very well so I use other well-known and tested products such as Malwarebytes and TrendMicro to augment the WD.
It's also possible you've gotten a lemon computer, and that happens occasionally. If you've had it less than 1 yr. or you have an extended warranty up to 5 yrs. taking it back to your place of purchase would be a prudent decision. I'd recommend you get another brand of computer if the shop you got it from is offering you an exchange or a refund such as a Store Credit. We didn't hear back from you on the result of your test with an external monitor or a TV with HDMI or VGA port, so can't comment on that part. Generally, that's a fairly conclusive test.
Just some thoughts for you to consider.
Best of luck and let us know how it goes.
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