It really sounds like you installed something other than Microsoft
Service Pack 3 for Windows XP. It also sounds like you may have an
infestation/infection of some type/many types.
You should probably uninstall whatever it is you installed. Control
Panel --> Add or Remove Programs --> Show Updates (checked). Remove SP3 if
it is there. Also, take note of the other software
that is listed. See if your NIS is still listed, see if your games
are listed, just make a nice list of everything. As for the
various Windows/Microsoft updates you will see - take note of the
recent ones (install date, right side) and the ones that were
installed on/after the date you did all this.
If it is Windows XP SP3 you speak of, here is the removal
instructions:
How to remove Windows XP Service Pack 3 from your computer
http://support.microsoft.com/kb/950249
Now - cleanup that machine.
Download, install, run, update and perform a full scan (separately)
with the following two applications (freeware versions are the ones
to use for this):
SuperAntiSpyware
http://www.superantispyware.com/
MalwareBytes
http://www.malwarebytes.com/
After performing a full scan with one and then the other and
removing whatever they both find completely, you may uninstall
these products, if you wish.
Download and run the MSRT manually:
http://www.microsoft.com/security/malwareremove/default.mspx
Reboot.
Download the latest version of the Windows Update agent from here
(x86):
http://go.microsoft.com/fwlink/?LinkID=91237
... and save it to the root of your C:\ drive. After saving it to
the root of the C:\ drive, do the following:
Close all Internet Explorer windows and other applications.
Start button --> RUN and type in:
%SystemDrive%\windowsupdateagent30-x86.exe /WUFORCE
--> Click OK.
(If asked, select "Run.) --> Click on NEXT --> Select "I agree" and
click on NEXT --> When it finishes installing, click on "Finish"...
Reboot.
Then follow the instructions here:
How do I reset Windows Update components?
http://support.microsoft.com/kb/971058
Reboot.
CHKDSK
How to scan your disks for errors
http://support.microsoft.com/kb/315265
* will take time
Defragment
How to Defragment your hard drives
http://support.microsoft.com/kb/314848
* will take time
Ensure your hardware drivers are up to date (from the hardware
manufacturer's respective web pages.)
Reboot.
Log on as an user with administrative rights and open Internet
Explorer and visit
http://windowsupdate.microsoft.com/ and select to do a
CUSTOM scan...
Every time you are about to click on something while at these web
pages - first press and hold down the CTRL key while you click on
it. You can release the CTRL key after clicking each time.
Once the scan is done, select just _ONE_ of the high priority
updates (deselect any others) and install it.
Reboot again.
If it did work - try the web page again - selecting no more than
3-5 at a time. Rebooting as needed.
The Optional Software updates are generally safe - although I
recommend against the "Windows Search" one and any of the "Office
Live" ones or "Windows Live" ones fornow. I would completely avoid
the Optional Hardware updates. Also - I do not see any urgent need to
install Internet Explorer 8 at this time.
Once it is cleaned up - I suggest you install some plain antivirus
(free is fine) software, use the built-in Windows Firewall and get
the machine back up to service pack 3 status ASAP.
1) Download the full SP3 installation file.
Windows XP Service Pack 3 Network Installation Package for
IT Professionals and Developers (works just as well for you.)
http://www.microsoft.com/downloads/details.aspx?familyid=5B33B5A8-5E76-401F-BE08-1E1555D4F3D4
2) Reboot right before you try to install SP3.
3) Disconnect from the internet before installing (physically
disconnect - pull the network cable or disable the router/modem.)
4) Disable your antivirus and antispyware applications when you are
about to install SP3. Usually right-click on the icon in the
taskbar gives you a choice to do so.
Install SP3 by running the downloaded executable. Reboot when
requested to do so. Logon and let the machine 'settle' for about
10 minutes. Reboot. Give it 5 minutes after logon to 'settle' -
reboot.
After that - there will be more updates. Repeat the steps above
that had you visiting the
http://windowsupdate.microsoft.com/ web
page.
Want more specific instructions/list of applications/etc - please
ask.