I JUST had a similar issue yesterday and have resolved it, but first, as stated in the last reply, what are your PC specs? What is your processor, ram, graphics card, and hard drive setup? And what operating system are you running? I have 2 other options to offer, but one of the depends on your operating system (Windows 7, 8, 10?) You may or may not have to try what I am going to say here if the issue is your pc specs.
If you have a decent machine you can try this option. I am not sure if this option alone fixed my crashing issue in Vegas or not, as I did this option as well as what you did with turning the GPU acceleration off. So, if you went into Vegas to options/preferences/video and turned off 'GPU acceleration of video processing' already, that's a good start. But there is also another option you won't find in the standard preferences section that you may need to change.
When in Vegas Pro 13, go to the preferences tab again by going to options/preferences, but this time, hold the 'Shift' and 'Ctrl' keys down, THEN click the preferences options. Inside preferences, there is now an extra tab called 'Internal'.
In the 'Internal' tab at the bottom, you will see 'Show only prefs containing' with a little text box next to it. In that text box, type in 'Enable multi-core rendering for playback'. You should now only see 2 options in that list, with "Value" and "Default" columns next to them. If 'TRUE' is next the 'Enable multi-core rendering for playback', double click it and type in 'FALSE' in all caps. Apply the changes, close Vegas completely, and relaunch it. Try whatever it is you are doing that keeps initiating the crash, and see if it is still doing it.
If you are still having issues, we can take a look at other options.