Hi Harry,
We have had problems with the Anca software similar to this many times and 
that exact problem just recently. Last time, even opening the "Calctest" 
file output by the reprocessor program di not help us and we are simply 
using a separate installation of the software that is working properly on 
another computer to reprocess.
In a number of cases, this sort of fault is fixed by deleting and re-writing 
the setup (*.SET file).
Here's the checklist that I would go through: have the integration settings 
(*.apd file) in the setup been changed? Try the running setup file with no 
APD. Are the ref gas and sample peak integration windows correctly declared 
as such in setup? (a common fault with me). It seems as if the set file gets 
corrupted from time to time and it also seems as if changes made are not 
saved, therefore my trick of chucking it out altogether

The sample list must have the same setup for every sample. The samples must 
be declared correctly in the sample list as sample+reference delta 
(calculated vs ref gas pulse) or as separate sample and reference (delta vs 
solid standards)

None of this is guaranteed to work

From my experience with the previous Anca, I got very quick at reinstalling 
the whole software, with working backups of the .SET, .REF .SRC etc files

Good luck

Robert