Thousands of office printers around the world have been spewing out page after page of gibberish because of a computer virus.
Reports from companies reveal that thousands of pages of paper were wasted when the Windows virus hit their PCs.
Security firms said the worst hit were large businesses in the US, India, Europe, and South America.
The culprit is a malicious program called Milicenso that has been re-used many times by hi-tech crime groups.
In a blogpost analysing the virus, security firm Symantec said Milicenso was first seen in 2010 and because it was a "malware delivery vehicle for hire" had turned up regularly ever since.
Its most recent incarnation was as a tool for distributing French language adware. Symantec said Milicenso could infect a PC by various routes, such as an email attachment, via a compromised website or by posing as a fake video decoder.
Once installed, the virus polls a location on the net and re-directs web traffic so it serves up adverts.
Symantec said one side effect of infection was to generate a file in a PC's printer queue. This turns the contents of the files in the virus's main directory into print jobs.
"The garbled printouts appear to be a side effect of the infection vector rather an intentional goal of the author," said Symantec.
Victims hit by the virus have reported its effects via discussion forums run by security firms. In the worst cases, hundreds of printers have been generating gibberish and wasting reams of paper.
Security firms have now issued updates that should spot Milicenso and clean up any infections.