Keyboard not responding after changing users

[hardhu]

Hello everybody, I have this strange problem that is driving me crazy.
In a Notebook with Win 7 x64 Ultimate, there are two users (user1 and user2) both belonging to administrators group.
If I do the following steps: first login with user1, then disconnect, then login with user2, then disconnect, at this point the laptop keyboard does not respond anymore, that is I cannot input anything and also led in Caps Lock and Num Lock do not turn off if I press the buttons. On screen keyboard instead works.
I have tried to uninstall and reinstall keyboard drivers, with no luck.
I have tried to boot in safe mode, and the issue is still present.
I guess there is nothing more to do than reinstall Win7, but if anybody has some suggestion I would be happy to read them.

 

[Megahertz07]

By "disconnect" you mean logout or switch user?

Let's do the basic.
Open a CMD window as administrator and type:
chkdsk c: /f
It will say your disk is in use and if you want to schedule to next start = yes.
restart
Pay attention on the results, specially bad blocks, bad clusters, bad sectors etc..
Back to Windows, Open a CMD window as administrator and type:
sfc /scannow
Report

 

[hardhu]

By "disconnect" you mean logout or switch user?

Let's do the basic.
Open a CMD window as administrator and type:
chkdsk c: /f
It will say your disk is in use and if you want to schedule to next start = yes.
restart
Pay attention on the results, specially bad blocks, bad clusters, bad sectors etc..
Back to Windows, Open a CMD window as administrator and type:
sfc /scannow
Report

Thanks for your reply, I have done the the basic.
Chkdsk seemingly reported no issues. I took a picture of the screen before rebooting which showed:

[...]
0 bad file records processes
2 EA records processed
143 reparse records processed
[...]
0 unindexed files scanned
0 unindexed files recovered
[...]
Usn journal verification completed
Correcting errors in the volume Bitmap

This last one was the only worrying message, but notebook restarted before I could take a picture of subsequent lines, sorry.
Also sfc /scannow gave me only "No integrity violation found".
As for your first question, I meant logout, but also switching user produces the same issue.

 

[Megahertz07]

Open Device Manager. Is there any yellow alerts of missing drivers?
And when you have the keyboard issue?

 

[hardhu]

Open Device Manager. Is there any yellow alerts of missing drivers?
And when you have the keyboard issue?

No missing drivers, I tried again to uninstall and reinstall drivers, and the issue is still present.
By the way, I discovered that even if I just log out from user1 and try to login after with user1, keyboard does not respond, that is the issue is not related to the presence of the second user.
I appreciate a lot your efforts to give me suggestions, but I am afraid that if anybody has never experienced this problem by himself, it could be almost impossible to find out which is causing it.

 

[Megahertz07]

In all my years setting up computers I never seen a issue like yours.

Keyboard is a hardware device with its driver.
User profile is loaded after all hardware are loaded and set. Changing users should have no effect to a hardware device.
Sorry, can't help you.