Hello Alberto,
I remember a very old Sybase bug (Change Request 304902) where the root cause was identified as is:
If the last parameter of your stored procedure is not passed by reference (e.g. INPUT) and previous parameters mapped to your DataWindow columns are defined as INPUT/OUTPUT, a PowerBuilder crash may occur.
You can find the CR description here: Sybase Search Results
Enter 304902 in the 1st field
HTH,
Jacob
