Apple Computer warned that some of its latest iPods have shipped with a Windows virus. The company said that a small number of video iPods made after Sept. 12 included the RavMonE virus. It said it has seen fewer than 25 reports of the problem, which it said does not affect other models of the media player, nor does it affect Macs. The company apologized on its Web site for the problem, but also used the opportunity to jab at Microsoft, its operating system rival.