Using context menu actions causes "virtual sticking" of ALT, how to fix this bug?

Question

Iron

Hello. I have the following problem: when using the functions of the context menu of any, something like a virtual sticking of the ALT key occurs. That is, I click on the object with RMB and select some action with the object from the context menu, then after that if you click on the object, using LMB or ENTER, its properties open instead of opening it. The glitch appears periodically and only after using the context menu. Additionally: Checked for suspicious programs and cleaned Autorun - everything is clean, checked the disk and system, chkdsk & sfc / scannow, for integrity - everything is fine, the mouse is configured correctly, changed the keyboard and mouse - did not help, reinstalled the OS - did not help, the OS is clean not assembly, reset BIOS settings - did not help. Temporarily, the bug removes pressing the right ALT. I read that it could be a problem with the motherboard. Tell me, please, what could be the cause of this bug, how to check the motherboard, and other PC components, for the cause of this bug or another way to solve it? Thank you in advance.
Update: I noticed that for the most part this bug appears when scanning objects through the context menu using ESET Internet Security 12. After scanning through the RMB with this antivirus, pressing (LMB or Enter) on any object opens its properties instead of opening it. The bug is removed only by pressing the right ALT. After that everything opens normally.

Answer 1

The bug has been fixed. The cause of the bug was a conflict between the antivirus and some kind of software. Replacing the antivirus with a different version helped fix this bug.

Answer 2

I also observed this, after using the RMB, pressing the LMB called the context menu.
I met on different computers in different cities and even on a laptop, treated by pressing RMB again.
There was a feeling that this is some kind of Windows bug.

Answer 3

and a sloppy keyboard is not an option? for example stuck alt
turn off the keyboard, check the menu operation without it