Antivirus provider Panda Security was left scrambling for a solution after it mistakenly flagged itself as malware.
The incident caused Panda to quarantine crucial files, in some cases preventing users from logging into Windows. On Twitter, the company was warning users not to reboot their PCs until it had fixed the problem.
As of Thursday, Panda had automatically pushed a replacement for the faulty signature file, preventing any further lockouts.
Panda also produced a recovery program to restore the quarantined files on PCs where problems persist. Users must download the file and enter some instructions in the Windows command line before running the executable. Some users may have to start their computers in Safe Mode to get past the Windows login screen.
Why this matters: While this incident may seem amusing--at least for those unaffected--it's hardly an isolated case. As The Register points out, plenty of other antivirus vendors have wreaked chaos through false-positives, including Kaspersky, Avira, Sophos, and even Microsoft, whose free antivirus software has flagged Google Search and Chrome as malicious on separate occasions. While some work is being done to fight false-positives through whitelisting, it's unlikely that this is the last time an antivirus program will run amok.