Maya render

Hi,

I installed Maya2011 on imac cor2do but when i tried to do Maya Software Render with quicktime.mov output it usually gave me with qt extension file, this was in 2010 but when i installed 2011 and tried to render it with same old settings, render is creating the file while at render time with the qt extension but when finished file is vanished. ? what could i am missing can some one point me ? any help will be appreciated.


Thanks
Asad Kazmi