Just an update. Update 4 has been installed on the said system a 700MB test file copied to an external HDD. The copy was successful. So it looks like the problem has been resolved. Further testing will prove that.
BTW something not mentioned. His system is a dual boot Linux system as well which has Parthnope as the SLB. So on every Kickstart update the file must be duplicated on a boot volume. His Workbench is formatted with FFS2 DOS7 which the SLB can't understand.