Commonwealth Bank has revealed statistics showing that over the last five years it has managed to wrangle the number of major computer crashes it endures each year down from 66 to ten.All the banks are keen to reduce the number of Severity 1 incidents (classed as a computer failure for which there is no obvious workaround) they face, but CBA and Westpac are the most transparent in terms of their progress.Westpac's CIO, Bob McKinnon, said last year that in 2007 the bank was enduring 30 Sev 1 incidents a month.  By the end of last year, the bank had wrestled that down to around nine a quarter - still worse than the CBA's claimed run rate of 2.25 Sev 1s a month, but a huge improvement on its previous record.The problem for bank clients, however, is that a Sev 1 incident at one bank can lead to cascading problems at all the banks, as payments between banks fail to complete.While it's never going to be possible for any bank to eradicate all systems failure, all of the majors are investing substantially either in core system modernisation or upgrading the fabric of their existing computing infrastructure, partly to reduce the number of system failures but, more importantly, to allow them to react more nimbly to changing market conditions.Commonwealth Bank's $1.1 billion core banking modernisation program is now more than half completed, with all retail transaction and saving accounts having been migrated to the new platform. That real-time banking platform will now act as the foundation for new mobile financial applications that the bank plans to launch later this year.Outgoing chief executive Ralph Norris said yesterday that the planned mobile applications were "not just about competing with banks, but with telephone companies, new social media and technology companies", which are increasingly encroaching on the payments arena.Norris said that the development cost of the mobile applications was "quite modest", but depended on the overhaul of the core systems, which comes with a $1.1 billion bill. "For what we are announcing, you have to have a real-time core platform," he added.Although the bank revealed that the $730 million core banking modernisation budget had blown out to $1.1 billion at its half-year results, this is partly due to its being expanded.Norris said yesterday that the figure had not changed since then. However, he said, the bank had not "expensed anywhere near that amount".  Norris also revealed that only 25 per cent of the core system modernisation budget would ever be expensed, with the remainder being capitalised over a decade.