Global shipments of personal computers fell 14% in the first three months this year, research firm IDC has said - the sharpest plunge since the firm started tracking the industry in 1994.
The figures come after a year of bad news for the personal computers.
Consumers, especially in wealthy countries like the US, are steering their dollars toward tablets and smartphones rather than upgrading their home PCs.
It is the biggest challenge to the personal computer since the IBM personal computer was released in 1981.
In an attempt to keep the PC relevant, Microsoft released a radical new version of Windows on October 26. Windows 8 has a completely new look and forces users to learn new ways to control their machines.
"Unfortunately, it seems clear that the Windows 8 launch not only didn't provide a positive boost to the PC market, but appears to have slowed the market," IDC Vice President Bob O'Donnell said.
The newest version of Windows is designed to work well with touch-sensitive screens, but the displays add to the cost of a PC. Together, the changes and higher prices "have made PCs a less attractive alternative to dedicated tablets and other competitive devices," O'Donnell said.
Another research firm, Gartner, reported an 11% decline in PC shipments in the quarter. That, too, is the sharpest decline it has seen since it started tracking the market in 2001.
Hewlett-Packard, the world's largest maker of PCs, saw a 24% drop in shipments in the first quarter compared with the same time a year ago.
The industry's number two, China's Lenovo Group, is benefiting from sales to first-time buyers in China and other developing countries. As a result, it held sales steady, alone among the world's top 5 PC makers, according to IDC's figures.
However, Gartner noted one bright spot - businesses are buying more PCs, and account for about half of the market.
Both firms track shipments of PCs from the manufacturer rather than retail sales. Shipments correlate closely with sales. The figures include shipments of Apple's Macs, which account for about 5% of the worldwide market.