I was having the same problem. After updating Construct 2, Construct 2 would quit immediately each time I opened it, preventing me from running it at all. I didn't see any item in the registry for "HideStartPage",
so I just followed your instructions and created a new DWORD registry entry with a value of 1. I tried launching Construct 2 again, and now it works!
Thank you very much! That problem had prevented me from using Construct 2 for months. Much appreciated!