A firm had £32,000 worth of IT equipment damaged by an employee with a grudge.
A credit controller has been jailed and fined after being caught deliberately sabotaging the computers at his workplace.
Edward Sobolewski had asked his employer, market research company Frost and Sullivan, for a pay rise, but his request had been refused, the Daily Telegraph reports.
He decided to take revenge and began taking cleaning products including Cillit Bang into the office to empty them into servers and other computer equipment.
Astonishingly, he did this between 2009 and 2012 before bosses became suspicious, repeatedly bringing IT systems to a halt and causing failures.
When asked why he was walking around with cleaning products, he told other staff he was simply cleaning the office and this was not questioned further until computers repeatedly began to crash.
Managers eventually installed CCTV cameras and caught 44-year-old Mr Sobolewski red-handed.
He has now been sentenced to eight months in prison and ordered to pay £10,000 costs to cover some of the £32,000 damage he caused on his wrecking spree.
The judge criticised Mr Sobolewski for causing extra tasks for his colleagues, who often had to work longer hours to replace documents that had been lost and to investigate what might be causing the IT failures.
"It was out of character. He has pleaded guilty and I would say he has come to his senses," his lawyer commented.
Late in 2012, intelligence services in Britain and the US were alerted after a government employee in Switzerland went rogue and downloaded huge quantities of paperwork onto portable hard drives.
It is thought he intended to sell it on, although it is not believed he had the chance to do this before being found out.
Although most employers would hope they do not have staff holding such a grudge against them, these situations highlight the importance of proper data protection and archiving.