The following files could be find them in C:\WINDOWS\SYSTEM:
mfc30.dll, olepro32.dll, msvcrt20.dll, mfc40.dll, msvcrt10.dll, msvcrt40.dll
So, the problem must come from the missing key DB4C0D00 in registry list. However, I couldn't re-install the registry by following your steps. I did them for a few times but couldn't re-install the registry successfully. Was there something missing?

When I used add/remove from control panel to remove VFP, Win95 still ran the setup program of VFP. Did this step correct?
After removing VFP, the setup program told me to restart the Win95. Should I do it?
When I remove leftover files, before or after the window restart?

Sunny