what specific complaints did those protestant reformers have with the prctices of the medieval church. I got because the church clergy began to give jobs to their relatives who were undeserving for this right, and began to take lots of money.
That's an accurate answer. :-)
These sites will help you with that.
http://www.google.com/search?hl=en&ie=ISO-8859-1&q=+protestant+reformers+%2Cmedieval+church.&btnG=Google+Search&aq=f&oq=&aqi=
Check this site particularly.
http://en.wikipedia.org/wiki/Martin_Luther#The_start_of_the_Reformation