I had the failed autoupdates this week...the first that I can ever recall in my experience with Windows. I eventually installed them manually one by one, e.g., download, install one, reboot, and repeat for the next. That worked like a charm (I had around 8 updates). No issues with Vegas after the full round of updates.
I had issues with Win7 auto updates as well. I surmised that the updates would not have been released without testing them first - but that they may not have tested all of them together as a group installation - given the permutations. Installing each update individually works like a charm.