Something gone wrong with my osx (10.9) and I cannot play .mov files. When I try to open a mov file, it displays me a message from Quicktime, titled 'coverting...'. This is not normal. I try to open file with video players like movist or vlc, they always opened mov files, always! I suspect that 'cleanmymac' maybe trashed something useful. Because when I attach an external hard disk with cloned image of my osx system, but in a previous state, the mov files are opened, with movist or vlc player running not from internal hard disk but from the external one. I shut down the external hard disk, I try to open files, the 'converting' message of Quicktime appears. It makes me feel strange because I think that especially vlc, does not depend on codecs, I think it have anything it needs by itself. I tried repairing disk permissions but nothing changed. What goes wrong and what should I do to fix it?