I tagged on "cash_fan1" s topic call for help, I FOUND the same problem, as I could not Connect to Banks and Government Websites.
I contacted my ISP and on their advise, removed the following:

AD-WARE
SPYBOT S & D

and leave AVG and Windows Defender.

This did not solve the problems yet, as there were two obstacles to fix:
msg 0x800106a - Windows Defender
msg 0x800b0001 - Windows Update

Windows Defender had to be removed.
Installed a series of DLL's. under REGSVR32 XXXXX.DLL
Then re-installed a fresh copy of (free) Windows Defender.
Then ran MS Windows Update.

Problem Solved.

Thanks for letting us know. Do you remember what dlls were re-registered?Was it a list like this ONE:
regsvr32 softpub.dll
regsvr32 wintrust.dll
regsvr32 initpki.dll
regsvr32 dssenh.dll
regsvr32 rsaenh.dll
regsvr32 gpkcsp.dll
regsvr32 sccbase.dll
regsvr32 slbcsp.dll
regsvr32 cryptdlg.dlllet me get you the story:

------------------------------------------------------------------
To reinstall Windows Defender, visit the following Microsoft Web site:
http://www.microsoft.com/athome/security/spyware/software (http://www.microsoft.com/athome/security/spyware/software)

3. If this issue is not resolved after you complete step 2, follow this step:a. Click Start, click Run, type regsvr32 + one space + file name, and then click OK.

Note In this step, file name is a placeholder for the following files.

Repeat this procedure for the following files:
• wuapi.dll
• wuaueng.dll
• wucltui.dll
• wups.dll
• wuweb.dll
• atl.dll
• softpub.dll
• wintrust.dll
• initpki.dll
• mssip32.dll
-------------------------------------

from:
COMPAQ, Windows XP Home Edition, HP Total Care:
Help and Support Center: windows defender

You are most welcome.


Thanks...I'll definitely try those steps on next "victim"
BTW...removing Windows Defender: http://www.microsoft.com/athome/security/spyware/software/about/faq.mspx#EJAACI've been suspecting some Window update to cause this problem, and after some more digging, I THINK Windows Defender update KB890830 may be a culprit. I still need someone with the same problem to test it out.