You're not giving us much to go on Lyris.
While I don't have the lasted version, I haven't experienced that problem in Vegas versions 1 through 10... except for occasional pilot error.
Um, it's not wasting any time for most of us. Because it's not happening for most of us.
Maybe some specifics as to the nature of the project (# tracks, plug-ins used, etc) as well as something a bit more meaningful in your system specs, and we might be able to make some suggestions.
Lyris, I have found that if I'm rendering to a networked drive and the drive is in "sleep mode" the file will be empty after render. However, if I wake the drive or re-render the file after the drive has awakened the file renders properly. Is this perhaps something you are experiencing?