upgrades

When did this start happening? What sort of errors are you getting?
What SP do you have installed?
Microsoft stopped support for SP2 so if that's what you have, you need to download SP3 and install it before trying to run any other updates.

 

Run malwarebytes http://majorgeeks.com/download.php?det=5756
Do the Quick scan, not the full or flash (flash is only available in the paid version).

 

Go here

Code:

http://www.microsoft.com/downloads/en/results.aspx?pocId=7&freetext=&DisplayLang=en

In the drop down box, select Windows Security (it's at the bottom)
When ALL the security updates are displayed, click the Released column. It will order from newest to oldest or oldest to newest. If it is not the order you want, click again so 4/6/11 is the first update showing. There are no April updates for XP yet. The first applicable update is the 8th item down which is only for 64 bit windows. You are probably running 32 bit so skip that.

Look for this update
Update for Root Certificates [March 2011] (KB931125) dated 3/21/2011 and see if you can download and install it.

Please post any errors you get.

 

You downloaded the file even though you get a message saying that the page can't be displayed and you see the page to download that update?

What version of Internet Explorer are you running? I think maybe a browser fix might be in order.

Was this the downloads page I linked you to or another website?

 

Hi

What security software do you have installed apart from AVG (is AVG the free version or retail/paid)? please name all.

If you disable AVG can you get Windows update to work? if not then reset the Windows Update components HERE with the FixIT and try again. If you get any errors please write them down verbatim and let us know what they are.