Internet Explorer isn't the only browser companies are being urged to drop due to ongoing security problems. Hewlett-Packard (HP) is now also recommending users erase America Online's (AOL) Netscape browser from their hard drives due to a hair-raising list of "potential" vulnerabilities allowing denials of service, information leaks, unauthorized access and remote malicious code execution.

In an advisory issued on Monday, HP said it will no longer support Netscape for its HP-UX version of Unix, and urged users to switch to Mozilla, the open-source project on which Netscape is based. At a time when IT managers are considering ditching Internet Explorer due to ongoing security concerns, HP's move underscores the fact that few are now looking at Netscape, which once sparked the Web boom, as a viable alternative.

"Netscape is no longer being updated for HP-UX. It should be removed, and Mozilla should be used instead," HP said in its security alert. The HP-UX version of Mozilla is available from HP's website.

The Mozilla project was founded in 1998 in order to take advantage of the open-source development model, in which developers have access to software source code and are free to use it to create derivative products. Netscape hoped the project would spur faster development, but it was 32 months before a commercial browser emerged. In the meantime, Internet Explorer took over the browser market -- benefiting from Microsoft's dominance of the desktop rather than from better technology.

Last year, Time Warner's AOL subsidiary distanced itself from the browser it inherited from Netscape, first signing a seven-year deal to continue using IE, and then spinning off Mozilla into a nonprofit.

On Windows, years of IE dominance have made switching away from the browser all the more difficult, according to industry analysts. Users are familiar with IE's user interface, and furthermore many mainstream websites are dependent on the browser's technologies and rendering quirks. However, IE's very popularity -- it is used by about nine in ten Web users -- has made it the target of ever-more-sophisticated attacks, security experts say.

On other platforms, such as Linux, Unix and the Mac, IE is less of a threat. Microsoft said it would scale back IE development for the Mac after Apple introduced its own Safari browser, based on the open-source KHTML rendering engine. Microsoft doesn't make a version of IE for Linux or Unix, where Opera Software ASA's browser or those based on KHTML or Mozilla are the norm.

Besides Mozilla, Opera is the only browser that can claim to run on Windows, the Mac OS and Unix-like operating systems; a stripped-down version also runs on Symbian OS, embedded Linux and other mobile devices.

Opera admits its browser suffers from the same compatibility problems that plague other IE competitors, but argues that the problem is naturally on its way out. "With the advent of the wireless Internet, Webmasters must start complying to W3C standards, or else their pages will not be accessible to the majority of the Internet population," the company said in a statement on its website. "The two dominant browsers on the PC are too bloated to fit into small, handheld devices."