I’m not at home (where my Vegas machine is), but I believe the mxf.sfl file is created by Vegas when rendering but is NOT the output file you want. If I’m not mistaken, that is the file that Vegas uses to display the audio waveforms for your video.
You didn’t give a lot of info on what type of file(s) you are trying to render or what format you are trying to render them to. One thing to watch out for: Your rendered output file will go into the folder you last rendered into, unless you specify otherwise. This may be important if you are rending output to (what you think is your current folder), when it’s actually going to the “last used” folder. As an example: I keep all my given files for a project in a top level folder with the year and project name (i.e. 2008 Austin Lake). If I last rendered a file to that folder (because that’s what I was working on), then the next time when I start a new project folder (say 2014 Varsity Football) and render output, it will go into the Austin Lake 2008 folder rather than the folder I am now working in (Varsity Football 2014). You must make sure and navigate to the EXACT location you want your output put into when you give the output file its file name, or Vegas will output it to the folder last used. I don’t know if that’s what’s happening here or not (not enough detail given).
I understand your frustration – for anyone to be able to help you, give as much detailed info as possible including what you are trying to do, and what you are/are not getting.
Andrew Lenczycki