Further setbacks in the release schedule for Windows Vista revealed last week hint that problems with launching the OS (operating system) may be broader than Microsoft has admitted.

Beta testers familiar with Microsoft's plans to release test versions of the OS said that although the software giant has claimed Vista development has been delayed only a few weeks, the date it will be released to manufacturers has been pushed back two months.

Instead of reaching manufacturers on 25 August, as originally scheduled, Vista will now be released to them on 25 October, sources said. The next CTP (Community Technology Preview) release of Vista, the completion of the Beta 2.0 cycle, has been moved to 24 May from its original release date of 12 April. Similarly, the first release candidate of Vista, originally set for mid-July, is now slated for 25 August.

Microsoft said it is on track to release the next CTP of Vista in the second quarter, but has not given a more specific date than that.

In a hastily scheduled conference call last Tuesday, Jim Allchin, co-president of Microsoft's platforms and services division, announced that the consumer versions of Vista would not ship on PCs until January 2007, though business customers will have access to the OS before the end of the year through the volume-licensing channel. This means Microsoft and its hardware partners will miss selling Vista PCs during the busy Christmas shopping season in the US between late November and late December.

Allchin characterised the delay in development as "a few weeks" on Tuesday's call. But a two-month change in the manufacturer release data clearly suggests development is off track by more than that. Moreover, analysts said missing its target date for the Christmas period gives Microsoft breathing room to push back Vista's release even further into 2007.

PC sales are typically slower in Q1 and Q2, said Joe Wilcox, analyst at Jupiter Research. "Microsoft missed the holidays, so January might as well be July," he said.

Even a late October manufacturer release is bumping up against a deadline for when OEMs (original equipment manufacturers) would need Vista in order to get the system on PCs in time for January, Wilcox added.