An anti-virus software labelled itself as malware, causing some computers it was running on to stop working.
Essential components in two Panda anti-virus programs became corrupted after an update, leading them to be mistakenly identified as malign.
Panda said a fix had been released and warned that rebooting computers could affect the systems.
It asked those affected to get in touch so it could help fix their machines.
Professor Alan Woodward of Surrey University said: "People's first response is to turn [their computer] off and back on again, but in this case it seems like the wrong thing to do."
Panda security said the signature file in both its PCOP and Retail 2015 packages became corrupted.
It said: "The signature file was repaired immediately. Additionally, a solution for all affected products has been automatically deployed. However, in certain environments it is possible for the incident to persist."
It added a list of steps that affected users could take to ensure that their system was clear of the issue.
Professor Woodward said this was not a great advert for Panda. He said he had heard of some companies losing the use of multiple computers to the issue and that data loss was a risk if machines were rebooted.
Panda security said however that it was helping people whose machines had stopped working to restore them, and that it had no evidence anyone had experienced permanent data loss as a result of the issue.
A spokeswoman at Panda security said: "We have solved 90% of the incidents, and support is being given in real time to the ones that still have some issues."
Return to internet news headlines
View Internet News Archive