The problem is caused by a bug which requires that your computer's resolution must be the same as the game's resolution setting at startup. There are three known fixes for this.

A) Change your screen resolution in windows to 720p
B) Start the game. It should start up fine.
C) set the game's resolution to what you normally have
The game will crash!
D) restore your screen resolution in windows

Fix Two:
A) Navigate to C:\Users\XXXXX\Saved Games\Codemasters\ToyboxTurbos
B) Open video_settings.xml (or, if it's not there, create a file with that name"
C) ensure the contents of the file are exactly as follows:

<?xml version="1.0" encoding="UTF-8" ?>
<config width="1920" height="1080" fullscreen="true" msaa="true" brightness="0.500000" depthOfField="true" smoothingType="-1" VR="true" VRRenderFactor="1.000000" />

A) navigate to the folder (XXX\Steam\steamapps\common\ToyboxTurbos)
B) Right click on "ToyboxTurbos.exe" and select properties
C) Check "Run in 640 x 480 screen resolution"
D) Start the game. It should run fine.
E) set the game's resolution to what you normally have
The game will crash!
F) Right click on "ToyboxTurbos.exe" and select properties
G) Uncheck "Run in 640 x 480 screen resolution"

If none of the above fixes work, try the following:

some people have reported a need to change the properties to "Run this porgram as an administrator" and/or "Run this program in compatibility mode for:". Try "Windows XP (Service Pack 3)" first. If that doesn't work, try "Windows 98 / Windows ME"

A) navigate to the folder (XXX\Steam\steamapps\common\ToyboxTurbos)
B) Right click on "ToyboxTurbos.exe" and select properties
C) Check "Run this program as an administrator"
D) Check "Run this program in compatibility mode for:"
E) Select "Windows XP (Service Pack 3)"
If that doesn't work, select "Windows 98 / Windows ME"

If this still doesn't work, get a refund.