We have had the same problem with our tasks in publisher. We use group reduction (divid the source appliction into smaller applications) and load the aplications at the same time. For that we need more CPU affinity to keep the speed up. It is also importent to increase the maximal number of simultaneous QlikView engines for distribution (that could be done under System/Setup/Distribution Services/Advanced). Our is set to 100.
Could u show us a part of the log?
For some weeks ago we had a problem with a virus that affected our tasks in publisher. We contacted Qliktech and they advised us to make a change in the register because the virus made us run out of sessions.