go.google.com and anti virus pages blocked

Had a look at a PC that was not updating AVG free, or letting you get to any anti-virus or anti-spyware websites.

Manually downloaded and updated AVG and Spybot - Spybot found fraud.pchealth and a couple of other gremlins, but AVG would still not update.
When I googled something and clicked on the link, a new tab opened in Firefox and it went to another search page - the links appeared to be going via go.google.com
Checked hosts files, tcp/ip settings, proxy settings, dns settings. Ran Hijackthis and Spybot again, but still nothing, but still problems with browser forwards, and AVG failing to complete a scan as the services would stop then restart when a scan was initiated.
Finally googled go.google.com and found a link on the techguy.org website:
http://forums.techguy.org/malware-removal-hijackthis-logs/746850-go-google-redirect-virus.html

Followed these instructions
http://www.bleepingcomputer.com/combofix/how-to-use-combofix
which then ran, found some rootkits, rebooted, and continued scanning and then removed the rest of the virus - tdssserver from memory (i'll get a copy of the fix log)

Rebooted and then downloaded malwarebytes.org and ran that - left the user with orders to run superantispyware and AVG after malwarebytes had finished running; AVG found a trojan within a couple of minutes and deleted it.

Had a call to look at someone's PC - the BBC iPlayer wouldn't work, neither would internet banking, and McAfee Security Centre was blank when it loaded up.

I ran IE7 as administrator (Vista Home Basic) and it worked fine - tried this with McAfee as well and that also worked, so i thought it may have been a permissions issue.
Turned down IE7 security settings, but still nothing, so started Googling it...

Found this link on the McAfee site:

http://service.mcafee.com/FAQDocument.aspx?id=107121&lc=1033

And tried this part of it:

1. Click Start and select Search.
2. In the Search box, type CMD and click OK.
3. In the Search results window, right-click CMD and select Run as Administrator.
4. In the command prompt, type REGSVR32 JSCRIPT.DLL and press ENTER.
5. After the confirmation message is displayed, type REGSVR32 VBSCRIPT.DLL and press ENTER.

It then says to uninstall and reinstall McAfee, but i tried it straight away and it worked for everything without any reinstalling needed.
Rebooted just to make sure it still worked and all ok.

Not sure what caused it - whether a Java install got corrupted or something, but all sorted now.