A California law firm has filed suit against handheld computer maker Palm and its former parent company 3Com, claiming that a feature used to synchronise data between Palm's handheld computers and a PC can cause damage to motherboards.

The suit, filed last week in San Francisco's Superior Court by Pinnacle Law Group alleges that Palm and 3Com failed to warn users that the so-called HotSync feature in Palm computers could damage certain models of PCs, resulting in those people needing to buy a new motherboard for their computer. Specifically, the suit charges that the HotSync feature can disable the serial port on certain brands of PCs.

Palm has denied that it knows or has heard of situations where HotSyncing can damage a PC.

Filed on behalf of two California Palm owners, the suit seeks class action status for others in the US who bought certain models of the Palm V and Palm Vx and who may have been affected by the problem. The allegedly defective Palms were sold since 1999, and the law firm estimates that 'hundreds of thousands' of users were affected.

The lawsuit seeks unspecified monetary damages and an injunction, requiring Palm to warn users that its PDAs (personal digital assistants) can harm their PCs.

Pinnacle first heard of the problems occurring with PCs from Dell. However, following media reports about the suit, the firm has now received emails from people who have also mentioned the problems occurring on systems from Gateway, Compaq, a Toshiba notebook and even an Apple said Andrew August, an lawyer with Pinnacle.

The scope of Palm models affected has also increased, August said. "Now we've been getting emails from people with [Palm] IIIcs," August said. August estimated that, following media reports of the suit, the firm had received anywhere between 12 and 30 emails from people who had suffered similar problems while Palms were connected to their serial ports or USB (universal serial bus) ports.

"Palm is not aware of any HotSync operation that will cause damage to computer motherboards," Palm spokeswoman Marlene Somsak said.

However, one user wrote in an email to IDG News Service that she had experienced a serial port failure "more than once, with more than one PDA and PC". When she contacted Palm about the problem around December 2000, Palm user Amy Langill said a technical support representative from the company told her that "'floating voltage' caused by the power supply to the Palm V cradle caused it to physically damage serial ports on certain motherboards."

"They advised us to purchase a USB cradle which would not have such issues," Langill wrote. "We opted to stop buying Palm Vs instead."