I guess its 32-bit compatibility issues, with the latest version of operating system and old version developer product. Or if your Oracle homes have been messed up with couple of installations and deinstallations.

Try copying those files, otherwise reinstall after deleting the
HKEY_LOCAL_MACHINE/SOFTWARE/ORACLE.Make sure you want to do this. IF you have anything important don't do this and find workarounds.

What version of OEM you are using ? Make sure your OEM repository database processes(init.ora) is more than 200, otherwise you get all the kinda errors.