Hi Sabrina,
You can go to the events file and add an event handler for the OnLogError event.
On the script that controls the event you can check the priority of the error.
Now, I use this to stop the test if the priority is bigger than 300 (mostly it happens when TC can't find an object), but for your case, you need to change the priority of that checkpoint (wich I dont know how) or do it by script with an if and a log.error(priority=400 for example).
If this is what you want and can't do it, please tell me and I'll give you the code.
Hope it helps