A. The problem:

Toolbox Client starts, displays splash screen, but the application window disappears immediately after that, leaving a process in the Task Manager. 

At the same time Toolbox Server display the following error: System.TypeInitializationException: The type initializer for '<Module>' threw an exception. ---> System.BadImageFormatException: Could not load file or assembly (see Figure 1) 

Figure 1

As a result, the Toolbox server is running only.

B. Description of the problem: 

Windows antivirus application will sometime have false positives where it will mark Toolbox as a virus.

C. How to solve the issue

To fix that you need to allow Toolbox from the “Virus & threat protection”, following the steps outlined below. 

Step 1: Click on “Virus & threat protection” in the Windows search (Figure 2)

Figure 2

Step 2: Click on “Protection history” (Figure 3)

Figure 3

Step 3: Click on the last blocked application (Figure 4)

Figure 4

Step 4: Click on “Actions” and then “Allow” (Figure 5)

Figure 5

Step 5: You can now start the QSAR Toolbox.