Yes, I have tried to manually create a new file (based on the 2 that works) but ArcMap does not pick up the extensions anyway. Does it matter what order I have on my clsids and catids?
Also, I would suggest ESRI to implement a /errorlog parameter to esriRegasm.exe so that I can see the detailed errormessage if the registration fails. Now it very hard to troubleshoot why it is failing.