This issue occurs on Windows laptops with AMD or NVIDIA graphics card, when the performance setting for Vegas in the graphic card's software is set to Optimize Graphics Performance.
AMD graphics card
Right-click anywhere on the desktop and choose the AMD Catalyst Control Center or Configure Switchable Graphics.
Click Browse, add Vegas Pro.exe or Vegas Movie Studio.exe to the list of applications, and then choose High Performance instead of Power Saving.
NVIDIA graphics card
Right-click anywhere on the desktop and choose the NVIDIA control panel.
Click Manage 3D Settings.
Click Program Settings and add Vegas Pro.exe or Vegas Movie Studio.exe . Change the preferred graphics processor to High-performance NVIDIA processor.