Dell in the US is offering free replacements of the displays on nine popular notebook PC models, responding to customers who created a Web site to complain that some LCD screens developed a one pixel-wide vertical line.

"Dell shipped faulty LCD screens in 2005 and is giving customers grief about replacing the screens. It's time to bring attention to the issue," says the site, "Managers at Dell need to be made aware of the issue so that they can stop treating their loyal customers like dirt and replace the screens in a timely fashion."

Unless a faulty screen is replaced, it can develop a permanent vertical line one pixel wide, either stuck on a single color or reflecting the color displayed behind it, according to the Web site.

Dell first responded to the issue in April, offering to replace certain 17-inch displays on Inspiron 9200, Inspiron 9300 and XPS Gen 2 notebooks sold between November 2004 and October 2006.

On Tuesday, Dell expanded its replacement program to include six more models, including the Inspiron 6000 and 8600, Latitude D800 and D810, and Precision Mobile Workstation M60 and M70 notebooks sold between December 2004 and December 2006. Some of those models use a faulty component that can generate the line over time, according to a posting on Dell's corporate blog by Lionel Menchaca, Dell's digital media manager.

Dell will now replace any LCD screen affected by this issue within three years of purchase, or will refund customers who were forced to pay for their own replacements, Menchaca said. Dell did not respond to requests for comment about the size of the program, or say whether the manufacturer of the faulty component would help pay for it.

The recall happens at a time when Dell is struggling to comply with an accounting investigation by the US Securities and Exchange Commission, maintain its listing on the Nasdaq stock exchange and reverse a market share slide that has allowed rival HP to claim the title of world's largest PC vendor.

In response, CEO Michael Dell launched the corporate blog in February, announced he would lay off 10 per cent of the company's workers and has begun selling PCs in retail shops such as Wal-Mart. Retail store distribution is a sharp break with the company's history of selling computers only directly through its Web site and phone lines.