However, the formulation for that prediction is based on Microsoft's past missteps, not specific problems in the ambitious and long-delayed operating system.
In a report titled Windows Vista Unlikely to Ship Before 2Q07, Gartner said it did not think Vista, which is expected to be released at the Windows Hardware Engineering Conference (WinHEC) in Seattle later this month, would be ready before the second quarter of next year.
The conclusion is based on how things went with past OS releases. It took 16 months for Microsoft to ship Windows 2000 after its second beta, which was a very troubled release.
Windows XP took only five months to go from Beta 2 to final code. Windows XP, the report noted, was not as ambitious as Windows Vista, which made the testing cycle easier.
Michael Silver, vice president of client platforms at Gartner and co-author of the report, said the latest builds are better than earlier ones, but his conclusions are based on the amount of testing that needs to be done.
''This release is a whole lot more complex than Windows XP and 2000. So how will it take them less time to test a more complex product?'' he said.
Even though Windows Vista uses the same kernel at the heart of NT 4, Windows 2000 and Windows XP, it's been heavily modified to accommodate new technologies. The User Access Control in Vista goes into the core of how apps are run.
So while there are some similarities to NT 4, Windows 2000 and Windows XP, Microsoft is making enough changes to make it problematic, said Silver.