Dell and Toshiba have posted information on their respective Web sites advising customers with certain models against upgrading to Windows 98 in the near term. The warnings come a week after Microsoft launched Windows 98 to a mixed reception. While some corporate and consumer customers say their upgrades to the new operating system went more smoothly and seamlessly than any previous upgrades, others have been vocal about the many installation and setup problems they have encountered. Users are also complaining that they have met with constant busy signals when trying to call Microsoft's no-charge technical support line. "We're sorry about the busy signals. This is mainly a volume issue with product support caused by the fact that we've sold more copies of Windows 98 than we expected," said Rob Bennett, Microsoft group product manager. Bennett declined to release Microsoft's projections for Windows 98 sales and said the company had yet to corroborate the 530,000 copies of Windows 98 that PC Data, a market researcher in the US, claims were sold between the launch of the product on June 25 and Sunday, June 28. Meanwhile, some hardware vendors are taking matters into their own hands in terms of providing support for Windows 98 customers. Dell for example is warning users of many models of its Latitude corporate notebook against upgrading to Windows 98 on its Latitude home page until they obtain as-yet-unavailable patches and BIOS updates. Dell offered users of other systems, such as its Inspiron notebooks, downloadable modem card and video driver patches to enable them to upgrade immediately to Windows 98. "Please be advised that the new features in Windows 98 will require a new set of system drivers in order for the operating system to function properly. In some cases, an update to your system BIOS may also be required," reads the notice on the Latitude Web site. Toshiba advises certain notebook customers not to upgrade on its Technical Support Web site. The company warns that users whose notebooks are ACPI (advanced configuration power interface) enabled should not upgrade until Toshiba posts upgraded BIOS and driver software for each model on its Web site. Those notebooks are currently without BIOS and driver support to make ACPI work, officials said. Toshiba is working on the drivers now and will post them as soon as they are ready, the officials said. They noted no other problems with Windows 98. While Compaq does not advice against users upgrading to Windows 98, the company provides an extensive list of possible conflicts with the operating system. IBM has also posted a number of patches and warnings to users. Gateway and Hewlett-Packard offered no information on Windows 98 conflicts. ZDNet UK News has asked Microsoft UK for a reaction to the current situation with Windows 98. We expect to post a UK story by late afternoon. We are interested to hear what your experience with Windows 98 has been. Do you have concerns? Is Microsoft guilty of releasing software that hasn't been tested properly? Let us know. Mail the Newsdesk