A processing system for assisting computer programs running in a distributed computer system is disclosed, the processing system including: a detector for detecting that a running program has encountered a problem caused by not having direct access to another piece of code; a requisitioner for obtaining the other piece of code from another part of the system; and a controller for controlling the computer to re-run the program from a point before the problem was encountered, in such a way that it has the necessary direct access to the other piece of code.