New message that my Windows 7 is not genuine

Since a few weeks, I am getting a little popup saying that Windows cannot be activated. Even after rebooting the computer, that message has not gone away.

Since about a week, I am getting different messages about my Windows 7 not being genuine.

On the bottom part of the desktop it now says:

Windows 7
Build 7601
This copy of Windows is not genuine

Often, I get a popup in the corner asking me to activate my key. It says:
Activate Windows now
The activation period has expired.
Click this message to start activation.

Then at other times, I get a popup saying:

Optional update delivery is not working

You may be a victim of software counterfeiting.
To use all Microsoft windows features, such as all
updates from Windows Update, get the latest updates;
and receive product support, your copy of Microsoft
Windows must be validated as genuine

And i also "lost" my desktop as it is only black now.
I rebooted my computer today, thinking it would go away, but it didn't.

Any idea what is going on?

Is this a computer that came with the version of Windows you are now using pre-installed, or did you install a copy of Windows 7 on it? Post the make and model of the computer.

It is a "used" computer that I bought, about4 years ago, and Windows 7 Professional was installed by the shop at that time.

It is an Acer desktop computer.

I had brought it back to the shop in August 2016 to reinstall Windows after some issues I had when beta testing a program.

Did they give you a genuine Windows 7 disc with Product Key? It sounds like they may have installed a dodgy copy of Windows. If you had a disc and Product Key, you could call Microsoft to get the issue resolved. If not, it may be back to the shop for assistance, but there are no guarantees that the issue won't pop up again later.

Thanks. I contacted the shop and they will do a remote session to fix this issue. It should be done tomorrow. If it is still a problem, I'll let you know :)