Yesterday, being the second Tuesday of the month, Microsoft released a handful of updates. Among them is Security Update KB913446 (http://support.microsoft.com/?kbid=913446). For some reason, when I went to the Windows Update web site, all updates install correctly except this one (KB913446, MS06-007: Vulnerability in TCP/IP could allow denial of service). The site simply reported that the update failed and gives no reason why (although C:\Windows\WindowsUpdate.log seems to indicate that there is a problem downloading and verifying the update). I had to manually download this update for it to install. This happened on four different machines I tried it on.
I called the (866) PC-SAFETY (727-2338) number Microsoft lists on their site and spoke with a Microsoft Technical Support representative who informed me that there was a known issue downloading this particular update.
On a similar topic, I downloaded the new Windows Defender (beta 2), which is Microsoft's new, renamed antispyware program. After upgrading, I was unable to update spyware definitions from within Windows Defender. I was finally able to get the latest spyware definitions for Windows Defender via the Windows Update site. (Source: BetaNews)