Microsoft was aware of the problem by late Friday, when someone identified as Darrell Gorter, who claimed to be with the company, asked users to send him log files "to determine a cause for the issue." On Monday, however, a company spokeswoman had little more to offer. "We are currently looking into this but have no additional information to share at this time," she said. "We apologize for any inconvenience this may be causing our users."

Messages left on support newsgroups, in fact, show that the problem was first reported by users in December when Microsoft offered a Vista SP1 release candidate to the general public, but required them to download and install the prerequisite updates manually, one after the other. The complaint volume picked up last month when Microsoft opened a second, more finished, build to all comers.

Some users remained frantic because they did not have a Vista install or recovery disc; computer makers often forgo such niceties, instead putting the recovery files on the PC's hard drive. Others took Microsoft to the woodshed.

"What blows me away is that Microsoft has not posted anything on the site yet, at least nothing I could find," said redwinger in a message to the newsgroup on Sunday. "They should at least say, 'We know we have an issue and we are looking into it.' I bought the laptop with the OS loaded and I don't have the recovery disk. How screwed am I?"

Although it's impossible to gauge the extent of the prerequisite reboot problem from the support forums, the traffic on the Windows Vista Service Pack 1 (SP1) newsgroup is substantial: the thread to which Melk, Gorter and phazedoubt posted included nearly 80 messages by midday Sunday, and had been viewed more than 23,000 times.

Two weeks ago, Microsoft announced it had completed SP1, and was sending it to resellers for installation on new computers, and to duplication to prep retail copies. At the same time, however, it said it would not make it available to most users until mid-March, and would not deliver it automatically via Windows Update until April.