The main reason is because many specialized video codecs have licensing fees attatched to them.If Vegas supported every video codec, it would add greatly to the cost of the software. #1 Convert your video into a Vegas friendly codec/format.
Soni Vegas offers support for almost all professional needs, including the ability to import data from multiple devices (including HD video), using more than 300 filters and special effects, special tools for working with text layers and translates easily optimize image quality, but as you might expect from Sony, focuses on as well as audio and video quality of the video track in general.
Do you know why I can't Import some files to Vegas Pro or Movie Studio ?
If you have been doing a lot of editing over many hours, then it is often a good idea to SAVE and do a RE-BOOT of your computer before you attempt to Render a Video.
Can you tell me your driver version also by going at Nvidia Control Panel? I did what the OP stated in this post, https://forums.creativecow.net/thread/24/993191 which was disabling every single Ethernet device that is labelled as "TAP-Win32 Adapter OAS", after doing that Vegas Pro 13 started up normally.
Sony Vegas Pro video editing package designed for professionals who need to produce high-quality HD video.