Metatrader Optimizer freezing on random passes

Hey I'm having this really frustrating problem where when optimizing an EA, it freezes up(the optimizer, not metrader or windows) on random passes. Sometimes it gets to pass 17 or 63, or 446, 782,ect but rarely past pass 1000. There are no error messages anywhere and its really confusing and difficult to troubleshoot. If it was a problem in the code, then I don't understand why on one try it would get to pass X and on another time get to pass Y.

has anyone experienced something like this?

During trading hours the bid-ask spread might change between every run of the tester, so it is not necessarily deterministic. Disconnect or try at the weekend and if it still behaves randomly then something unusual is happening.

Also make sure you have enough free disk space, it will create *HUGE* (really huge!) temporary files to store the simulated tick data.