Progress has been good, one analyst says, but the hard part of finding the "quirky" bugs can take from three to six more months, he says.
Research firm Gartner last week reiterated an earlier forecast that Microsoft won't meet the November corporate deadline, even though the developer is making progress in nailing down bugs.
In an online brief posted on the Gartner Web site, research vice president Steve Kleynhans applauded Vista's most recent build as not only stable enough to use day-to-day, but also as significantly better behaved than the original Beta 2, which was released to the public in May.
"However, there are still a lot of holes under the surface," said Kleynhans in the brief. He named graphics drivers as among the areas yet to be addressed.
"I've begun noticing a large number of small glitches and failures which can't be reproduced, and while performance is much better, it is also unpredictable. It's not unusual to find my system suddenly lock up for minute or longer," he added.
"Based on more than 15 years of experience with Microsoft beta programs, I'd say they are getting close, but they are into the hardest part of the testing: finding the corner cases and quirky bugs, a phase that can take from three to six months.
"While Microsoft is certainly making progress, I don't expect to see a finished product in November," Kleynhans concluded.
In the weeks before Vista went into Beta 2, Gartner analysts said that the next-generation operating system wouldn't make it into general circulation until the second quarter of 2007, months after Microsoft's own January deadline for consumers and November 2006 schedule for enterprise customers.
Last month, Microsoft executives continued to equivocate, saying that "There's no data or information that says we are not going to make the November business availability or the January  consumer availability," and at the same time promising Vista wouldn't ship until it was ready.
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