We have a system here. Recently there is a wrong calculation in one of the number in the report generated by the system. Through out our experience, we've never encounter any problem/error in this system for some years.
Because the writer of this system had already gone, we can hardly trace the programs. But we've verify the input data, the setting and they are right.
Now my question is, will a computer program suddenly go wrong without any logical reason? If I slam on the server machine, will one of the number which the computer is calculating, become another number and make the calculation wrong?
I agree my idea there is quite mad, but I just want to know, how can we know the problem is not caused by the program and the input, but some other factors?
P.S. This mad system has no log.