IBM delivered a stinging slap in the face today to the chipmaker that provides the brains behind many of its PCs: Intel. Big Blue announced that it will stop shipping personal computers using the Pentium chip because its problems are more significant than previously stated. Intel discovered a problem last summer in its chip but says the probability is so slim -- once every 27,000 years -- that it unlikely to cause problem. "We believe no one should have to wonder about the integrity of data calculated on IBM PCs," G. Richard Thoman, an IBM senior vice president, said in a statement. Intel, meanwhile, labeled the IBM move "unwarranted." While the announcement isn't likely to cause problems for Big Blue -- PCs that rely on the Pentium chip account for only one-fifth of total revenues from IBM PCs, which make up just 15 percent of IBM's overall business -- it's likely to put Intel in a funk. The company's stock tumbled at the NYSE, falling 2 3/8 to 60 3/8, but other manufacturers using the Pentium chip haven't announced whether they'll follow IBM's lead. Analysts say about 4 million computers using Pentium will be sold this year. While Big Blue probably made a sound business decision, "it's easy for IBM to say this," says TIME science writer Philip Elmer-Dewitt. "IBM is competing with Intel." Keep in mind that IBM is launching it's next wave of personal computers based on Power PC -- a chip being developed in partnership with Apple Computers and Intel rival Motorola.Post your opinion on theScience & Technologybulletin board.