Updated from 12:31 p.m. EDTThe personal-computer market took another body blow Friday morning when Dell ( AMD), the world's No.1 PC vendor, warned investors that its second-quarter results would fall short of expectations. Hot on the heels of mediocre quarterly reports from Intel ( INTC) and Advanced Micro Devices ( AMD), the two major microprocessor makers, the news wrought havoc on the shares of various PC players. Dell shares sank nearly 12%, or $2.65, to $19.45 in recent trading Friday, marking the stock's lowest point in four years, while AMD was down 13.4%, or $2.90, to $18.75, a 52-week low. Even Hewlett-Packard ( HPQ), which many believe is profiting at Dell's expense, saw its shares tumble more than 5% Friday, before moderating to a nearly 3% slide to $30.89. "Our take is that Dell's miss is largely about Dell, although it does add yet another reaffirmation about the state of the commercial PC market, mostly in desktops," wrote Goldman Sachs analyst Laura Conigliaro in a note to investors Friday morning. Goldman makes a market in Dell securities and has provided investment banking and noninvestment banking services to Dell within the past 12 months. For Round Rock, Texas-based Dell, the profit warnings are becoming a worrisome habit: Friday's warning marked the company's third negative preannouncement in its last four quarters. Dell's latest revision pegs sales for the quarter ending Aug. 4 at $14 billion, while its profit will range between 21 cents and 23 cents a share. Wall Street analysts were looking for Dell's second-quarter sales to total $14.2 billion, with earnings of 32 cents. Earlier this year, Dell ended its practice of giving specific quarterly guidance figures. At the time, though, the company said second-quarter results would be similar to the first quarter, during which it had sales of $14.2 billion and EPS of 33 cents.