Issue:

These issues include, but are not limited to:

• Gray or black viewports after an intensive render.
• Crash to desktop without error messages.
• Crash with Module Name: vrender20xx.dlr
• The Frame Buffer window freezes.
• Opening multiple sessions may also cause freeze. 
• Remaining idle when render is activated

Note: Different PCs may render the same scene without issue.

Causes:

Includes, but is not limited to:

• 3ds Max not running the latest update.
• Most recent V-Ray version is not installed.
• Not enough memory (RAM) is installed on the machine.
• Possible processor (CPU) issue within the computer’s BIOS settings.
• Graphics card (GPU) driver conflicts — outdated or legacy hardware.
• V-Ray version installed for 3ds Max is a mismatched version (for example, V-Ray for 2019 installed with 3ds Max 2018).
• Issues with Microsoft Visual C++ components (from program installs).
• Improper program or plug-in installation.
• Faulty memory

Solution:

• Update 3ds Max to the latest version
• Install the most recent V-Ray update
• Check that the PC has enough RAM
  Larger, more complex scenes, or scenes with higher render settings require more RAM to process the render. For these types of scenes, 32-64 GB of RAM is recommended so the scene does not fail while rendering. Also, if enough RAM has been installed it may be that the computer is not using all of its processor cores. 
• Update outdated BIOS or correct the PC’s CPU settings

Note: If there is an update for the BIOS listed from the manufacturer, install it as it helps provide the best software experience in Windows for the PC. To check if a BIOS update is required, use a Windows System Information file. System Information files (.NFO) can be found by doing the following steps:

1. Go to the Windows Start bar and type “System Information.”
2. In the System Information window, view the BIOS Version/Date field.
   
3. Use the File > Save option to save the file for review if needed.

• Update the graphics card or graphics card driver
• Correct any software and plug-in version mismatch
  Make sure that the V-Ray version matches the 3ds Max it is intended for. For example, V-Ray for 3ds Max 2019 is not compatible with 3ds Max 2018.
• Check for issues with Visual C++ components
• Check for Improper program or plug-in installation

If the previous steps do not resolve the crashing or freezing while rendering with V-Ray renderer, do the following:

1. Perform a Clean Uninstall of 3ds Max.
2. Uninstall V-Ray and any additional plug-ins (for example, iToo Software, VizPark).
3. Reinstall 3ds Max and all plug-ins.
4. Restart the PC and re-render the scene.

Source: Autodesk