Creative Technology has accidentally shipped almost 4,000 digital music players in Japan that contain a Windows worm, according to an advisory from Finnish security company F-Secure Corp.

The 5GB Zen Neeon players, which have been shipping for two months, contain the Wullik.B email worm, also known as Rays.A, F-Secure said. The worm is buried in a file in the Neeon's file system.

The worm will not infect PCs unless a user browses through the files on the player and clicks on the infected file, F-Secure said.

Creative, based in Singapore, did not immediately reply to a request for comment. The company has reported on its Japanese website that the worm affects players with serial numbers between 1230528000001 and 1230533001680, F-Secure said.

Wullik.B is more than two years old. It spreads by sending itself via email and dropping itself into shared folders.