I thought I might give some free (an worth it) advice on the next round of attempts. This distributed computation is somewhat related to viral computation, and I have learned a few things over the years that may be helpful in doing a better job of it. 1) Abandon the central command way of doing things. Little if any communication is required for this computation, it should be self-distributing to and between volenteer sites. That makes it ideal for implementation as a safe virus. 2) Give these computations a defined and limited lifetime. The problem you have with old versions is because they don't die automatically or even check to see if they are up-to-date and update themselves. 3) Use randomness to break up the search space and redundantly perform the computation. This should eliminate the problems with malicious key-space requests, etc. 4) Use feedback in the form of selective survival/replication to optimize the search and allocate search space. If a processor goes quickly, give it more to do - if it goes slowly, give it less. This will produce an overall system that adapts with time to the cahges in network and system usage so as to optimize overall performance as a function of time. -- -> See: Info-Sec Heaven at URL http://all.net Management Analytics - 216-686-0090 - PO Box 1480, Hudson, OH 44236