on Jun 11, 2014 at 10:35:36 pm Last Edited By Mike Kujbida on Jun 11, 2014 at 10:38:06 pm
Do you have QuickTime Player installed?
If you do, odds are that it's the latest version and may not work well with Vegas so try an older one.
I'm using 7.6.8 at home and 7.7.3 at work and have no problem playing ProRes files on either machine.
You can find older versions of QuickTime Player on this site