I seen this type of problem before. It was after an stall of Rage3d tweaker program. The folder that I ran the setup for that program from would keep opening when Windows booted up. I checked the startup folder and the other tings that were suggested above. Nothing could be found. What one person told me to do was rename or remove that folder. When I did this, it was fixed. You have watch out what folder it is because if it is a Windows operating folder, your system may not start - you have been warned. In the case I had, it was just a folder that I ran a setup program from.
I have also read that this can happen from a bad install of a program. With the machine I was working on, I un-installed the tweaker program and the folder would keep openning at startup. I ran the setup for the tweaker program again and after that the same folder would keep opening at bootup. The only thing that stopped it was renaming the folder that I found.