The Mobile Malware Researchers Association, a nonprofit organization of professional researchers, says it discovered the first virus that can be transferred from a PC to a mobile device and delete files.

The Association received an anonymous alert about malware dubbed the "Crossover" virus for its ability to cross-infect a Windows Mobile Pocket PC from a desktop computer running the Windows operating system. It's the first virus of its kind, according to the alert.

The virus makes a copy of itself and puts a startup command to the copy in the registry. It then quietly waits for an ActiveSync connection, which synchronizes data between a PC and a mobile device. Each time a PC is rebooted, the virus repeatedly copies itself into the registry. This could slow down the PC's performance or even stop it altogether.

The virus copies itself to a Pocket PC running the Windows CE or the Windows Mobile operating system and erases files in a device's My Documents directory.

But mobile users shouldn't panic just yet. The Crossover virus, like most of the mobile device malware that's surfaced in recent years, is a proof-of-concept virus. However, it shows a realistic scenario of how easily malware can spread from a desktop computer to a mobile device. And the alert was evaluated and posted by a vendor-neutral organization of researchers and doesn't appear to be an attempt by an anti-virus vendor to sell its security products.

Such threats will carry more weight as devices come standard with more features and run on faster wireless networks, leading to faster file downloads. And it's only a matter of time before hackers get more inventive with mobile viruses.