All signs so far point to Windows 8 being a flop.
"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.
In a statement, Microsoft described the PC market as "evolving and highly dynamic." Referring to a number that it has previously released, the company said it has sold more than 60 million copies of Windows 8 so far. That is "a strong start by any measure," Microsoft said. "Along with our partners we continue to bring even more innovation to market across tablets and PCs."
In its tally, IDC excludes tablets, even if they run PC-style software. It also excludes any device that has a detachable keyboard. With the release of Windows 8, PC makers have been reviving their experiments with tablet-laptop hybrids, some of which have detachable keyboards. Consumers are likely to have shifted some of their buying away from traditional laptops and toward these new devices, which means that the total sales decline of Windows-based devices might not be quite as drastic as IDC's numbers suggest.
Windows 8's poor sales start could amplify periodic calls for Microsoft to replace Ballmer, who replaced company co-founder Bill Gates as CEO nearly 13 years ago. "This puts a lot more pressure on Ballmer because Windows 8 is at the epicenter of all this," Moorhead said.
Microsoft, which is based in Redmond, Wash., will take questions from industry analysts April 18 when it's scheduled to release its latest quarterly results. Ballmer usually doesn't participate in those sessions.
Microsoft shares fell 55 cents, or nearly 2 percent, to $29.73 in extended trading, after the release of the sales reports.
Hewlett-Packard., the world's largest PC maker, saw a 24 percent drop in shipments in the first quarter compared with the same period a year ago. That was HP's steepest quarterly decline since the company bought rival PC maker Compaq a decade ago.
HP shares fell 60 cents, or 2.7 percent, to $21.72 in extended trading.
Meanwhile, the industry's No. 2, 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.
Dell Inc., the third-largest PC maker, suffered an 11 percent decline in the quarter. The bad news could be helpful to the Round Rock, Texas, company's attempts to sell itself for $24.4 billion to a group that includes CEO Michael Dell. Some shareholders believe the proposed sales price of $13.65 per share is too low, but Dell's board has argued it's a generous offer, given the deteriorating conditions in the PC industry — a point that may carry more weight now that the latest sales numbers are out.
Dell's stock dipped a penny in extended trading to $14.20.
Svensson reported from New York.
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