open up Vegas Pro as the administrator.
go to options, then preferences and Turn (OFF) GPU Acceleration.
then apply the setting's and restart the program as normal.
let me know if this helps, turning off GPU acceleration is the 1st method to fixing this problem and works 90% of the time
for most people.
I had the same problem with my Radeon HD 6850 when rendering in Main-Concept .mp4. The renders either got to 1% or 99% and then froze. After many weeks of on and off troubleshooting, I finally found a solution to my problems. I knew it was a problem with the GPU accelerated renders, so I focused my troubleshooting on that aspect. It turns out that if you are on windows 8 (or I believe 7) you can completely uninstall your Graphics card drivers (if on windows 8 DO NOT use AMD's driver uninstall cleaner utility as it will bug windows to the point where you have to do a system refresh.) , reboot and then go to AMD's website and install Catalyst Control Center 12.8 and it's drivers. Then reboot once more and you should have no more render freezes! This worked for me and I can t guarantee that it will work for you, but hey! it's worth a try right??
>>>open up Vegas Pro as the administrator.
go to options, then preferences and Turn (OFF) GPU Acceleration.
then apply the setting's and restart the program as normal.
let me know if this helps, turning off GPU acceleration is the 1st method to fixing this problem and works 90% of the time
for most people.