Help has arrived for anyone unable to install Windows Vista Service Pack 1 (SP1). Microsoft said this week that its latest update addresses problems in earlier versions due to bugs in an update required for installation.

The replacement update file should solve the problem that some customers encountered when they tried to install the original version of what's called the "Servicing Stack Update," or SSU, which is one of three updates required before SP1 can be installed.

Most users who downloaded the prerequisite update had no trouble.

However, for what Microsoft describes as "a few" users, the update gets caught up in a constant reboot cycle. In a nutshell, since Vista SP1 cannot be installed without it, those users who encountered the problem in the update were stymied. But now Microsoft said the problem's been remedied.

"Today, we’d like to let you know that we are resuming automatic distribution of the SSU," a posting on the Microsoft Update team blog said.

Microsoft first acknowledged the problem in late February, when it removed the update from download sites. After identifying the cause of the problem, Microsoft yanked the update.

"Microsoft is resuming automatic distribution of a prerequisite for Windows Vista Service Pack 1 and releasing a fix which will install prior to the SP1 Servicing Stack Update," a spokesperson in an e-mail. "This pre-SSU update helps to ensure a smooth install of the SSU by working to prevent the system from rebooting during the SP1 SSU installation," the spokesperson added.

Users who have automatic updates enabled in Windows Update will get the replacement without any further actions.