I have had this problem for quite some time, but never really got to it. I opened the Windows Update program to look for updates for my computer, but while checking for updates, I got this error:
"Windows could not search for new updates.
An error occurred while checking for new updates for your computer.
Error(s) found:
Code 80070002. Windows Update encountered an unknown error."
There is a red shield with a big X on the left side and a "Try again" button to click on the right side.
Here is a picture of the error I took:

Computer specs:
Windows Vista Home Premium Service Pack 2
AMD Phenom 9150e Quad-Core Processor 1.80 GHz
4.00GB Memory (RAM)
64-bit Operating System
Thank you,
Rakc