Virus, firewall, or registry problem blocking internet for windows update

Hello and thanks in advance for your assistance.

My problem is this: Windows update is unable to download anything from
the update servers. It alternates between an error that says it can't
connect to the internet, and an error that says it's already installing
other updates, but it is not. Additionally, AIM and Yahoo messenger will
not connect. I believe these are related somehow. I use firefox as my
main web browser. Both firefox and IE are working smoothly, with no
interuptions in my connection to the web.

I have had a number of recent changes to my system setup that could
potentially be to blame. I will list them below.

-Norton AV subscription ended and was not renewed, causing me to pick
up a number of viruses and rootkits.

-Used HijackThis and Malwarebytes to clean computer up, eliminating
some registry keys.

-Kept getting the viruses and rootkits back.

-Subscribed to Norton 360, which seemed to clear up all virus problems.

-Purchased a new router.

I'm running windows vista home premium 32 bit. I have a 2.2 GHz dual
core, HP. 500 gig HD, 2 gigs RAM, Gforce Video card with 512 onboard
memory, on a wireless N router/USB adapter. My PC came with vista
pre-installed, so I do not own a disk, only a restore partition.

Let me know if you need anything else, and again, thanks in advance.

At this point the smartest and most efficient thing you can do is back up
your data and clean install Windows.

If you want to continue to try and clean the machine (not recommended), post
your HijackThis log at of the specialty forums below.

Here are steps to rebuilding your system OS:

Perform a clean installation
There are two ways to perform a clean installation of Windows Vista. The
first method is to install Windows Vista by running the Setup program from
the current version of Windows on your computer. The second method is to
start the computer from the Windows Vista DVD. First, try method 1. If it
does not work, try method 2.

Warning In a clean installation, existing data on your computer is deleted.
This data includes personal data, settings, hardware driver information, and
software programs. After you install the operating system, you must also
reinstall all programs. Make sure that you back up personal data to disks or
other external storage devices before you perform a clean installation.
Method 1: Perform a clean installation of Windows Vista by running Setup
from the current version of Windows

To perform a clean installation of Windows Vista from the current version of
Windows on the computer, follow these steps:
Start the computer and make sure that the current version of Windows has
started.
Insert the Windows Vista DVD into the DVD drive and then close the drive
tray. Wait a moment for the Setup program to start automatically.
If the Setup program does not start automatically, follow these steps:
Click Start and then click Run.
Type Drive:\setup.exe and then click OK.

Note Drive is the drive letter of the computer’s DVD drive.
When the Setup program starts and the Install now screen appears, click
Install now.
When the Which type of installation do you want? screen appears, click
Custom (advanced). The follow the instructions to install Windows Vista.


OR:


Method 2: Perform a clean installation of Windows Vista by starting the
computer from the Windows Vista DVD
Note The computer must be configured to start from the DVD drive. For
information about how to configure the computer to start from the DVD drive,
see the documentation that is included with the computer. Or, contact the
computer manufacturer.

To perform a clean installation of Windows Vista by starting the computer
from the Windows Vista DVD, follow these steps:
Start the computer.
Insert the Windows Vista DVD into the DVD drive and then close the drive
tray.
Restart the computer.
When you receive the "Press any key to boot from CD" message, press a key.
Follow the instructions to install Windows Vista.

If Windows Vista is now running on your computer, you have completed the
installation successfully.

[ParetoL]

I had problem like this before and I just refer to pc health advisor and everything went smoothly. I'm not sure if this can help to you but try, nothing to lost if you try. everything happens in terms of registry cleaner.

I think an easy to keep your Computer from Running Slow is to install a PC protector or cleaning, according to my personal experience, Tuneup360 is good choice, and your computer takes only 30 sec to start up if you have it!!!