Problem Solved!!!
I'm working with 'time series' data and found where I had not moved one dimensioned variable into my Common Blocks along with the rest of the ones I had moved.
This Dimension eventually got exceeded as my data sets got larger, which caused the crash issue.
This code is "sphagetti code" which has migrated through various machines and compilers since about 1982.
I think we are good now.....
At least until the next crash happens
Thanks