As far as I know a D0 brane is same as a point particle. If that is true then its presence in string theory would go against the very philosophy on which string theory is based (due to presence of 0-dimensional objects). Is my understanding correct? Also it seems to me that D0-D0 brane interactions may lead to divergences in the same way as we face divergences due to point particle interactions under certain circumstances in ordinary quantum field theory. Am I right?