Research conducted by network services and Internet commerce firm Dimension Data found that while IT downtime was less extreme in the UK than in most other European countries, 88% of senior and middle management battle with network problems.
The pan-European survey of 450 managers across nine countries found that 70% of respondents were either mostly or totally reliant on their IT systems. Some 92% said they regularly lose hours of the working day, as a result of network downtime.
Some 8% of those surveyed said they lost three hours or more a week in network outages, a figure that rose to 14% in the UK, which Dimension Data said totals £35bn in lost productivity.
"When you add up the regular loss of working hours caused by system downtime, it becomes clear that companies need to focus on finding a solution to this problem," said Martin Chilcott, Dimension Data's global head of marketing.
The research found some 64% of managers surveyed blamed the IT department for the outages, while 40% said the resulting frustration led to some form of "computer rage" - hitting the PC, slamming a keyboard, throwing down a telephone or shouting at a colleague.