This is on Windows 8.1. My computer locked up two nights ago while trying to load something from GoG Galaxy. Nothing was responding, so I had to shut it off via the power switch. I left it for the night. When I turned it back on and logged into Windows the next morning I received two strange error messages I had never received before: "EPU.exe has not digital sign" and "GpuBoostServer.exe has not digital sign." Everything at first glance seemed find outside of these error messages. I tried to open GoG Galaxy again, but it didn't open or do anything. I clicked the icon and nothing. I tried to open Task Manager to see if it somehow started running in the background, but I received an error message when trying to open Task Manager:
"The program can't start because credui.dll is missing from your computer. Try reinstalling the program to fix the problem."
I wasn't sure how to "reinstall" Task Manager. I tried a few other programs just to see what would happen. Steam gave me an error that said "Failed to load steamui.dll" and Origin gave me an "update error." Chrome worked, so I searched some of the error messages. It seemed to indicate some files became corrupted from an improper shut down. This made sense, but I did a quick scan on Windows Defender anyway just to be sure. It found nothing and I was relieved, but I also like to run Malwarebytes, so I did. Another error message: "The specified procedure could not be found."
I posted on a couple of subreddits looking for help. I was still mainly thinking it was related to my hard shut down, but my only response thought it sounded like malicious software. He provided me a link to this website to download rkill and then another program once rkill did its thing. I tried every link provided on http://www.bleepingcomputer.com/download/rkill/, but each one gave me the same error message: "The specified procedure can not be found."
Are there any other programs that could help? I can't really think of what else to do besides just wiping everything and starting over... Any help would be appreciated.