The Microsoft updates ( called Microsoft’s Patch Tuesdays – second Tuesday of every month) are an important part of every Windows user’s and system administrator’s regular system maintenance. In fact, regularly applying fixes, patches, and updates should be part of your routine, no matter which operating system you use.
Windows XP update process sometimes gets stuck and shows a flashing yellow shield in the System Tray, indicating to download and install important security patches.
Fix for most common issue ‘Updates fail to install.’
In most cases a corrupted CatRoot2 folder causes this. You can fix this by renaming the \Windows\System32\CatRoot2 folder to CatRoot2OLD.
Note that you do not want to rename the \Windows\System32\CatRoot folder!
Now try again to get the update that failed to install previously. If this does not help, use the below detailed instructions.