According to my sources, Microsoft will soon ship an unexpected "refresh build" of Windows Vista to its technical beta testers and some corporate customers. Previously, the company had been shipping Community Technology Preview (CTP) builds of Vista to its testers and other audiences, including MSDN subscribers, only every month or two. I'm told that the refresh build is build 5342 and will require different product keys than the previous CTP.

"Microsoft is considering releasing updated Windows Vista code to TAP (Technology Adoption Program) customers in the coming weeks," a Microsoft representative confirmed. "Microsoft regularly provides our TAP customers with regular Windows Vista code releases and this upcoming code release is consistent with our past engagement with this group. The Windows Vista code will not be a CTP release. As previously announced, Microsoft expects the next CTP will conclude the Beta 2 process and we are on track to deliver the next CTP in the second quarter of this year. We have no information to share on the features or timing of the TAP release or the next CTP release and will follow up when we have more to share."

The Microsoft representative also told me that the company would ship an update to the Microsoft Internet Explorer 7 Beta 2 Preview code next week at the Mix '06 trade show. The IE 7 Beta 1 Preview was released in late January.

It's unclear why Microsoft has chosen to ship a Vista refresh build at this time, although I'm told the company is using it as a testing board for the extensive feedback it's gotten since the last CTP, which was issued in February. According to my sources, the refresh build will not meet CTP quality measurements and will ship only in the Vista Ultimate edition, for both 32-bit and 64-bit systems.

Microsoft originally expected to ship a CTP build in April, although that release could be pushed back until May, according to sources. That CTP should be made available to the public via Web downloads.