Ethnic divisions began to resurface in the 1990s, following the election of non-communist leaders throughout yugoslavia.

This is correct. After the death of Marshal Josip Broz Tito, Yugoslavia was ruled by a kind of a committee of leaders from all of the members of the Federation. This led to individual members of this "committee" to have arguments between themselves over power and in turn translated to members of the society, causing ethnic division to become important. An important conflict was between  Tudjman - Milosevic, between Croatia and Serbia, which caused the ethnic division to go out of hand.