1. Lay investiture - appointment of church offices by rulers instead
of church officials.
2. Worldly lives of the clergy - Bishops, Archbishops, Priests owning
a great deal of property and acting very wealthy including having affairs
outside of the church.
3. Simony - Appointing relatives to church postions.
4. Heresy - Speaking out against the doctrine of the church. (Inquistions
throughout Europe)
The Problem of Lay investiture was settled at the Concordat of Worms and the other issues were resolved at the Council of Trent and migration from Catholicism to Protestantism began to slow.