Windows 7 Pro - "domain" like login screen appeared

I'm setting up a new PC with the Windows 7 Pro. After some actions (software installing, config changes, applying updates ), my login screen looks like the PC is connected to the domain:

I have checked the settings and everywhere the "workgroup" is checked. I have been googling for three hours trying some solutions (Control UserPasswords2, regedit and the ".DEFAULT" key) but nothing works. I cannot see the user icons - only the login screen as above. I cannot also change the account icon.

Has anybody seen such an issue?

It could also be caused by a Group Policy. I don't have my Windows 7 machine handy, but I will update the instructions Tuesday when I'm at work...

1. Login as an Administrative user
2. Click Start, type gpedit.msc and press Enter. You may be prompted with a User Account Control dialog, just choose Yes
3. Navigate to Computer Configuration\Windows Settings\Local Policies\Security Options. On the left there is an option labelled Interactive logon: Do not require CTRL+ALT+DELETE that you can disable.
4. As well (and this is probably the one), go to Start, type regedit and press Enter. Again, click Yes if prompted. Navigate to HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System!LogonType. This should be switched from 1 to 0 (or vice versa, I'll have to doublecheck) to change the type. It's also under the policy editor from above, under the guise of Always use classic logon. I don't know which key though.

These effects claim to take effect immediately, but I'd still recommend doing a proper shutdown and reboot.

Sounds like Secure logon may have been enabled by a Windows update.

To remove the effect, click on Windows logo, type User Accounts, click the Manage User Accounts link.

Select "Advanced" tab, under Secure Logon, untick the Require users... and click OK (screenshot below).

Problem resolved!

The reason was the Dell Data Protection | Access software installed by default. The solution was to disable it via its settings - now I can see all the other local accounts and their icons, like you see when connected to a workgroup.

As I now know what was responsible for the issue, I can set it like I want to. The problem begun when, I think, I had changed the login rules via this Dell app.

I do appreciate your help and concepts. Thank you, though!