Johan my friend, please tell me you are new to LabVIEW. If you're not, then there's no excuse for using the nested Sequence structures, for not using subVIs, for the diagram size, etc. etc.
In any case, one of the problems I can see that may be the cause of the crashes is that you do not close your report references. You call the New Report.vi about 12 times, but never call the Dispose Report.vi. You must call the dispose for each new. See how this is done in this example: vi.lib\Utility\NIReport.llb\Dispose Report.vi.
Better still, since you seem to be referring to the same XLS file everywhere, you could open a reference to it once, and pass around this reference everywhere, using a shift-register perhaps??
See if that makes any difference.
-Khalid
