THANK YOU!!!
For me I did exatly what was in the thread you found. I deleted the registry below, restarted and it is all good now!
The answer is to open the registry editor (press Start and type regedit) and check the registry location below for a key called 'Shell'. For people experiencing this problem the key is there and it has a value of %comspec%. For people with healthy systems, that key isn't there. So simply delete the key and reboot!
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
I have been trying to fix this issue for almost a week now. Was about to wipe my system out of frustration. This worked for me too. I don't know why this happened but it was quick and easy.