Mac display turning grey when using iTunes

Hi, I'm a Korean so first I'd like to tell you that my English might not be perfect for explaining my situation now..

A few days ago, I installed "Significator for iTunes".(Ever heard of this program?) It's a application that helps you control iTunes on the menu bar.
Anyway, whenever I try to turn on the music, or move on to the next music, my display would turn grey for a sec and turns normal again. (It looks the same as when I use terminal to "killall Dock".

I tried to use iBoostup and CCleaner to get rid of the possible remaining caches from Significator for iTunes (ofc I removed this application first, but the problem didn't disappear so I tried to delete caches and so on).

So anyway.. now whenever I use iTunes, the display would turn grey for a second and it bugs me all the time.. I found some crashes at

/System/Library/CoreServices/Dock.app/Contents/MacOS/Dock

and

Monitor Panels and Display Panels (prefpane)

I don't know if these are causing the problems.. I tried to get my authentication from the Disk Utility back but although it says it solved the problems it's still the same...

I really don't want to re install my OSX.. is there a way I can fix this?
Please help.