Just as a first measure, restart all the QlikView services and try again. Kind of like rebooting your PC
qvb is the reload engine on publisher. I am assuming you know what document is reloading during that time? If this is a report that did not peg the server previously, you will want to look at a few things. First, was the qvw modified? If the script gets almost all the way through (check the log), then it is possible that a cross join or multiple fields being joined was accidently created, resulting in an overload on the CPU while it tries to resolve. Another possibility is that the underlying database changed. Maybe a table that previously was not populated, is now and has caused a huge influx of data that the qvw might not be equipped to handle. Are multiple docs reloading at the same time? This could also cause a problem as well.