The driver should not be causing assertions to happen. However, there should not be any call back into the driver from within the callback function, what product are you using so I can place a bug report.
Hi, one of our software engineers has had time to look at your query in more detail. Here is what he had to say
"The reason that the assertion occurs is that calling ps3000_stop will stop the
device streaming and also delete the overview buffers. It is not a valid
function to call especially as the overview buffers are currently in use."