Centalt appears to be down for me as well. Since KloxoMR uses yum to switch/replace applications the error is stopping you from being able to correct problems.
It appears you have nothing installed. Did you try to switch programs in panel? (Question, not asking you to do it) I am asking because KloxoMR will remove a program then use yum to add the new one. With yum not working, this is how you could have ended up with nothing installed.
mratwork-centalt serves httpd, so your webserver is down until centalt comes back or mustafa fixes the problem.