I think I know why it is caused but I dont know why it hasnt been fixed.
It is reporting that the engine cannot be started twice.
This should be a silent/filtered error used only internal to the software and not popped up to the user.

Hey Programmers! I dont mean to be a bother but please fix this !!
The detailed discription of the problem for programmers is this:
Right click and start ‘On Access Protection Control’
Stop/Terminate the Standard Shield.
If you click ‘START’ to restart the Standard Shield or process, the button click is sensed more than once or the process tries to start a 2nd time while it is already started and Avast 4.0 displays the Error 0x00046101 ,“Operation could not be completed” .
This is because the ‘operation’ is already done (start the Standard shield).

This bug should be easy to fix or ‘hide’ so it doesnt worry the end user of the program. Just have the program test to see if the processes are already running and if already running then ignore the input or report that the process is already running.

Help! Humans!
Sincerely,
Tim J.