It was billed as the House's last, big Y2K hearing of 1999.

Trying not to sigh, Rep. Constance A. Morella (R-Md.), who has chaired numerous Y2K hearings, said, "It is sometimes hard to believe that we have focused on this issue ever since the spring of 1996."

Once again, the White House's Y2K troubleshooter and his congressional watchdog from the General Accounting Office shared the witness table. The GAO testimony carried the title "Year 2000 Computing Challenge: Noteworthy Improvements in Readiness but Vulnerabilities Remain."

Out in the audience, a Y2K community action group handed out an "open letter" to Federal Reserve Chairman Alan Greenspan, urging him to speak out more forcefully on Y2K risks. "Disruptions will occur and in some cases those disruptions will be significant," the letter warned.

Yesterday's hearing, though, reflected little of the doom, gloom and tedium that marked early sessions and instead tried to sort out "Y2K myths and realities."

The consensus view, put forth by presidential adviser John A. Koskinen, is that the power grid, the phone system and the banks will operate normally in January, when many computer systems may misinterpret "00" as 1900, not 2000, and malfunction or crash.

Still, Koskinen said, "one of the more troubling Y2K myths is the notion that Jan. 1 is a seminal date on which everything, or nothing, Y2K-related will occur." Systems that have not been fixed will probably produce flaws in billing and financial reports well into 2000 as they process dates, leading to "possible slow degradations in service," he said.

Koskinen and the GAO's Joel C. Willemssen agreed that schools and colleges and the health care industry need to keep working to make sure their computers are ready for Jan. 1, given their late start on repairs.

But Koskinen suggested that any Y2K glitches would occur in isolated spots and suggested that Americans prepare for the holiday weekend by keeping copies of important records, stocking the pantry with a three-day supply of food and water and calling manufacturers to make sure home electronic equipment will work.

"Whatever people are going to do to prepare, they should do it early," he said. "If everyone waits until the last moment to take even modest precautions, supply systems could be overwhelmed."