First, if you've never looked at your update history, you can do so now by following these steps:
- Click the START button and then open the CONTROL PANEL
- Open the WINDOWS UPDATE icon
- On the left pane, click the link that reads, "view update history"
If you see a failed update in the list, note the update number (e.g., KB954366). After noting the number, check the updates above the failed one. If you see the same update installed successfully above the failed one, then you don't need to worry. Some updates need to be installed before others, so it may fail during one set, but install successfully later. That's okay.
If you see repeated failures on a specific update, then you may need to investigate further. You can search the update number in Google to see what comes up. Often times, the first link that comes up will take you the Microsoft page that tells you more about that update.
For example, on my computer the update history shows repeated failures for update KB954366.
When I search "KB954366" in Google, the second site in the list of results is to the Microsoft page explaining that update. Reading the page, I can see that this updates pertains to computers running the 64-bit edition of Vista. My computer is running 32-bit version, so it can't install that update (it's not compatible with my computer). So I can ignore KB954366 and references to its failure to install.
How do I know my computer is running is running the 32-bit version of Vista? I followed these steps to check:
- Click the START button
- RIGHT CLICK on Computer and select PROPERTIES
- Under the SYSTEM heading, you can check the SYSTEM TYPE (it will say 32-bit or 64-bit)