Hardware failures remain the most common cause of IT service disruptions, according to business continuity firm Sungard Availability Services, accounting for more than a third of all serious incidents.

SunGard's annual survey of business disruptions, released ahead of this week's Business Continuity Expo, showed an overall reduction in the number of major IT interruptions in 2007.

So while hardware failure was still the chief cause of interruptions, it accounted for 35 per cent of incidents in 2007, compared to 45 per cent in 2006. That suggests that IT leaders are getting better at protecting their mission-critical infrastructure.

But SunGard's Keith Tilley, executive president for the UK and Europe believes hardware failure is still depressingly common.

"Hardware failure can be potentially devastating in terms of business impact, but is relatively straightforward to plan around. The fact that it remains the number one reason for invocation indicates that our message - information availability should be considered at the highest levels of the organisation - has not yet got through," he said.

Other major causes of disruption included power failures (22 per cent of incidents); denial of access (7 per cent); and data corruption (5 per cent). The widespread summer flooding, outbreaks of foot and mouth disease and even bomb threats were also cited as causes of disruption.

Sungard based its figures on customer calls to invoke their business continuity agreements.