More dictation.
(Even with only four teeth I talk better that type.) 
I started studying computers around 1976 more or less. The first operating system I use was not really an operating system at all. It wasn't very early version of Microsoft BASIC that could only read and write files from a cassette tape interface. Yes, there was such a thing back in 1976.
For a few years in the late 70s I did some commercial programming and a company called
Dysan in Silicon Valley.(Not to be confused with Dyson, a different company.)
Anyway, back to the question at hand. Let's suppose that this error message is not really the whole story and do something else wrong with the computer. Given that you say this nothing important on the computer, doing a complete install of the operating system would be the most logical and reasonable recourse. The installation went also reveal if there are some serious problems with the hard drive or other components of the computer. If the operating system can be reinstalled successfully, that error message will not come up again. SBC said above, that program is not part of the operating system. It was inserted by a third-party application and for some reason that program is flashing the error message. But as I mentioned also, computers don't always give you the correct error message when something goes wrong.
Anyway, if you feel up to it here are your tasks.
First item is to find the product key for Windows 7 that is on your computer. Somewhere through the control panel or some other thing that should be a way to find the product key that corresponds to this computer. Also, you could look underneath the computer on the backside and see if there is a product key for Windows 7. You want to write down that information where you can find it when you need it.
Second task is to learn how to download an ISO file. In this context the term ISO refers to an image that is to be written to a DVD disc. You may need to use another computer to do that. It can take maybe a couple of hours to download the ISO file with a good Internet connection. The ISO file is found somewhere on the Windows site. Microsoft now allows people to download these image files for the operating system even without proof of having the product key. The program will ask for the product key later on during installation.
Now here's the third item. This task is to prepare a DVD disc using the ISO file. You will find a program that has the capability of making a copy of the ISO onto a blank DVD and also it will verify our guarantee that the DVD can be booted by the system. That can be the hard part. Just making a copy of the ISO is not enough. It actually is a forensic perfectly copied to the DVD in order to make it usable. It's not really that hard, but you just have to use the right tool. This is well documented elsewhere.
Now the fourth task is to get your sick computer ready to boot the DVD. That sick computer has an area called the B IOS, which is the firm are used to start the computer when you first turn it on. I am sure you must already know this, but I'm being redundant here because a lot of other people read this information and they will become disturbed or something is missing. Inside the firmware, also called B IOS, there is an area to specify which device will be booted first. You may choose to have the DVD boot first. Or there may be another option where you can manually select which device has to be booted. I can't give you that information off of the top of my head because there are so many different variations even on computers made by the same company. Now if it was one of my computers, I would have to press the F 12 key while the computer starting up and then it will proceed to be back me and tell me that it will do the boot menu after he gets new testing memory. And then when it gets new testing memory it will flash up a little set of choices then there'll be a choice for booting from the DVD or from the hard drive or from something else. At that point I choose the DVD and it starts to boot up and then I get a warning message saying that I have to hit another key if I really want the DVD to boot up. Dr. just get annoyed when the computer ask you for review and do something? If I didn't want to do it I would not press the key in the first place.
Okay, now is gone through for tasks and by now the DVD should be booting up and doing something and maybe providing some messages. At this point you're going to make a decision about what to do and it will probably destroy all the information on the computer. If you don't mind, you can just go ahead and do that. But you may find there's an option were the Windows 7 installation program will attempt to try to reinstall Windows on your system without destroying any of your personal data. You can try that if you like. If that doesn't work you could just go back and start the DVD over again from the boot up and make a different selection about how to install.
Actually, you might enjoy doing this. You might get to be next. On this and then show on your friends what you learn to do with your computer.
Now then, which links do you need? Someone you could probably figure out yourself.
Let's start with some place we can find the
Windows 7 ISO file that would be appropriate for your computer. You need to know ahead of time if you have the 32-bit or 64-bit version if you don't know or if it doesn't say, it's most likely the 32-bit version. Also, eating you know if it's the home version Horovitz the Pro version. I would guess it's the home version. What makes a difference is the product key. The product key is key for user the home or Pro version, but not both. Unless I'm wrong, which happens.
Download ISO for Windows 7 installer.
https://www.microsoft.com/en-us/software-download/windows7let me know if you are able to locate the product key and download the ISO file.
For Windows 7 the product key is still needed. If you had used Windows 10 it might not be needed. But you already said it's Windows seven, so let's just stick with Windows 7 and get the machine back to where it was.
Talk to you later.
