We reported earlier that there is a show-stopping bug with one of the prerequisite patches for Vista SP1 which is causing computers around the world to get stuck in an endless loop of reboots. <insert your own joke about improved stability and reliability here>
Microsoft didn't take long to evaluate the problem and respond:
“So far, we've been able to determine that this problem only affects a small number of customers in unique circumstances. We are working to identify possible solutions and will make the update available again shortly after we address the issue.
Customers who may be experiencing this issue can use system restore to correct it or contact 1-866-PC-Safety for help troubleshooting. Additional guidance will be available via Microsoft's free Update Support Center soon.”
Bottom line: no official fix yet, but it looks like we can probably expect one soon.