I don't recognize the steps you took, but I suspect they are from an old version and are no longer necessary, and may mess up correct registration. Hopefully someone else can be more definitive about this - I'm a relative newbie. Check the version you found this info for.
I strongly suspect that your registration for XML files is messed up in some other way as well. I don't believe it should be using OLE at all for normal invocation of the editor - Eclipse is trying to call some other program via OLE and failing.
Same stepts worked with eclipse 3.1