Windows 7: UAC randomly disabled

I pressed Win+R to open the Run dialog and noticed it said "This task will be created with administrative privileges" and had the little UAC shield icon next to it. Suspicious...
So anyway I opened the UAC settings, and sure enough, it's set to the minimum level, so I moved the slider back up to the top.



However, the whole system still acts as if UAC isn't enabled even after closing Explorer.exe and restarting it. Is it a sneaky virus at work?

Did you restart after changing the UAC setting back to high?

Is your user account an administrator account?

I'd recommend setting uac to its highest level and then rebooting. Then I would run a malware check with an updated version of Malwarebytes : Free anti-malware download and run a antivirus check with an updated anti virus program.

After I rebooted everything seems fine... although I'm still wondering how it was disabled in the first place.
Maybe it was just me being sloppy and forgetting to re-enable it after temporarily disabling it, or maybe it wasn't.