UppityNegress, the answer to your question has many variations. I will answer what I believe to be one of the main problems of African Underdevelopment.
We all know that Africa had a past before European colonization. However, after European colonization, the Middle Passage which took as many as 100 million Africans from all over the continent, and the division of African by the Euopeans for material gain; Africa began to go downhill.
European interference in African affairs has caused many problems since the rise of African and Asian revolutions. I include the affects of the Cold War on Africa. During that time frame the U.S. and Russia were actively fighting to gain control of the mineral and produce wealth of Africa. The Russian funding of the Aswan Dam in Egypt. The uranium for the Atom bombs that were used during WW II came from the Congo. DeBoers diamond mines are exclusively in South Africa. One can't forget the coups organized and incited by the USAID and USIA (US Information Agency) and the CIA implicated plots that kept wars and squimishes going on the continent. This was not only happening in Africa, but in Latin America as well.
I think that so many people as in any other forming or reforming parts of the world had people jockeying for power. Thus where the corruption issue comes in. Back in the day, there was a push for a unified Africa by Kwame Nkrumah and Patrice Lumumba. Lumumba was killed and Nkrumah for all his best efforts was overthrown by a US backed coup.
The constant warring and political instabilities in some countries have led to an unfortunate decline in the ability to provide things essential to build up a nation. This instability worked for the private European corporations to exploit many African nations and their people. Today the effects of all this are clearly seen by the underdevelopment in Africa.
Additionally, the natural resources in Africa are beginning to run out while the World Bank and IMF are dealing a double blow to poor nations who are seeking debt relief. They must privatize everything in their nation and open it up to more foreign companies, like water, electric, etc.
I think that now is the time for them to seek internal solutions to many of these problems. I mean by internal, reaching out to the descendants of those taken from Africa to work in conjunction to assist.