On certain Elo machines, Microsoft update KB3097877 causes a conflict with Elo Touch drivers. The conflict makes it impossible to log into Windows. To fix this error you will need to rollback update KB3097877.
You will need to shut the computer down and boot it in Safe Mode with Command Prompt.
The update can be removed from a command prompt with this:
wusa /uninstall /KB:3097877
You can also add the /quiet switch if you don’t want to monitor progress of the uninstall. It takes about a minute to uninstall.
A reboot is required.
The trick of course, is to get onto the machine so that you can run the command. Using RDP works. If RDP is not enabled you can use the Registry editor in System Repair to edit the following key:
Set fDenyTSConnection to 0
That should do it.