Can't install software or perform Windows Updates

For the last long while Windows Update has been failing on 99% of updates and (certain) software won't install. I have seen the error 0x8007010B in both cases. Why is this happening? How can it be fixed? I've searched all over for answers but I haven't gotten anywhere. I am using 32-bit Vista SP2.

Update: I found this really helpful looking page http://support.microsoft.com/fixit/ and downloaded a thing to fix windows updates and it said it found an issue where the location for updates had been changed and it said it fixed it but updates still don't work.

The error, 0x8007010B, is caused by the file directory being invalid. Locate and download the update or updates directly from Microsoft's Download Center. After you download the update or updates follow the steps below. (Credit: MowGreen's Post)

Perform a clean boot of the computer and then install the update

To manually perform a clean boot of your computer in Windows 2000, Windows XP, or Windows Server 2003, follow these steps:

1. Click Start, click Run, type msconfig, and then click OK.
2. On the General tab, click Selective Startup, and then click to clear the following check boxes:
   • Process SYSTEM.INI File
   • Process WIN.INI File
   • Load Startup Items
3. On the Services tab, click to select the Hide All Microsoft Services check box, and then click Disable All.
4. Click OK, and then click Restart to restart your computer.
5. Run Microsoft Update or Windows Update. If the update does not run successfully, go to Method 4.

Note: You'll find more information on this topic and the source at this Microsoft Support page.