I had similar trouble, have a program running for last 10 years written in VB6, now client wanted to make some major modifications, and all my machines which are now windows 10; failed to open the project, it was always that nasty mscomctl.ocx error. I had done lot of things but could not solve the problem. Then I thought the easy way around, I downloaded the latest mscomctl (
Then opened a new project, added all the components like mscomctl, activx controls etc, saved it and opened this newly created project file in Notepad, then copied the exact details and replaced in the original project.... and bingo! The old project opened up normally without any fuss! I hope this experience will help someone.