If you find a way to reproduce this problem just let me know, maybe it could be fixed inside DayPilot.
As far as I can tell something like this could happen if the page structure changes after the Scheduler is initialized. The latest sandbox build (8.3.3578+) includes improvements of runtime width detection. It should improve handling of the situations when the Scheduler width changes but the window width stays the same (i.e. changes of the page layout). You can test it to see if it fixes the problem:
http://www.daypilot.org/sandbox/
If it doesn't help you can try calling dp.show(). You can do it like this:
<DayPilot:DayPilotScheduler
...
ClientObjectName="dp"
/>
<script>
function fixView() {
dp.show();
}
</script>
You can call fixView() when needed - usually it's after the page structure changes but the Scheduler doesn't update itself properly. If you have problems with the initial page load but don't have a good event handler to hook you can simply call it after a certain delay (that's an ugly workaround but it should help):
<script>
setTimeout(function() {
fixView();
}, 200);
</script>