A bug in Kaspersky Lab's antivirus software caused the program to identify Windows Explorer as malware:
The security company's systems had decided that a virus called Huhk-C was present in the explorer.exe file, leading to its confinement or, in some cases, deletion. As Windows Explorer is the graphical user interface for Windows' file system, this made it difficult to perform many common tasks within the operating system, such as finding files.
David Emm, a senior technology consultant at Kaspersky Lab, told ZDNet Australia sister site ZDNet UK on Friday that the company was still examining its checklist to find out why the false positive "slipped through the net".
"This is classic false alarm territory," Emm said. "We will check through our systems and see if we can tighten them up so we don't run into this problem in the future. No antivirus company, including ourselves, can say they have never had a false alarm, [but] on all fronts, we do what we can to minimise any potential risk for our customers."