SEATTLE — A computer virus targeting Microsoft Corp.'s Windows software shut down machines yesterday at Time Warner Inc.'s CNN and Walt Disney Co.'s ABC network.

A CNN spokeswoman confirmed computer failures in in Atlanta and New York and said she wasn't sure which worm caused the damage. ABC computers on the East and West coasts also were affected, a spokesman said. He also couldn't identify the worm or virus.

The Zotob computer worm has been spreading since Sunday and affects machines running Windows 2003, 2000 and XP, according to anti-virus software maker Symantec Corp. Symantec rates Zotob, of which there are four variants, a 2 or "low" in severity with 5 being the highest. Microsoft's Windows runs almost 95 percent of the world's personal computers.

The worm takes advantage of a Windows flaw that Redmond, Wash.-based Microsoft disclosed on Aug. 9 along with a software update to fix the flaw.

A patch for the security hole is available at www.microsoft.com/technet/security/Bulletin/MS05-039.mspx

Shares of Microsoft fell 39 cents to $26.74.