McAfee Inc., a leading Anti-virus programme maker, has admitted that its update for a number of virus-scanning products caused chaos on Friday in corporate and consumer systems using the virus protection products. This was the result of a virus definition file triggering the quarantine or deletion function for several executable files, including Microsoft's Excel.

The problem occurred when the company released its DAT file -- or virus definition file -- No 4715 as part of a daily updating routine and intended to refine McAfee anti-virus products' capability to catch the W95/CTX virus. In a matter of minutes, the company's customers started seeing an unusual number of files being quarantined or deleted by scans using the newly-released update.

While excel.exe was the most affected, the list of exe files released by McAfee as having affected by the update was of seven pages. Users complained that the anti-virus programme tried to remove files including Perl, Sysinternals' PcTools suite, various Oracle binaries, Dell OpenManage, Google Toolbar installer and programs that run Macromedia Flash Player, Sun's Java application and Adobe update manager.
McAfee claims that it had reports from some 100 customers, and then immediately released an updated definition file, DAT 4716, which addresses this issue.