Vista, IE and Ping

[#1]

Hi all
A friend has a vista powered laptop that can't connect to the web. I've found the DNS server IP was wrongly configured and changed that (now obtaining automatically for ip and DNS) and it is able to ping any website on the web that doesn't have a firewall blocking ping.
IE still cannot connect to any websites 
Tried flushing the dns cache, resetting winsock, (which then grumbled about needing to be elevated despite being logged on as admin) etc. I'd reinstall vista for him but he's no ovista CD and drive D reports 0 bytes available or used.
Any ideas for a quick fix to get IE working for him? I've encountered this on a few machines but always got around it but this one has me stumped!

[#2]

Check under  Internet Options > Connections > LAN settings  that a proxy has not been set.
Does another computer connect using the same router?
Does Vista show the two terminals with globe in the Taskbar indicating it thinks it has an Internet connection?
Try Internet Explorer (No Add-ons) under Programs > Accessories > System Tools.
Uninstall any security software that includes a firewall.
Under Internet Options > Advanced, reset Internet Explorer.
Can any other program access the Internet?
Check the hosts file.
Run an virus scan for evidence of a DNS changer.

[#3]

Quote from: ReedRichards

Check under  Internet Options > Connections > LAN settings  that a proxy has not been set. Nope, checked that and all good Does another computer connect using the same router? Yes - tested my own netbook on there! Does Vista show the two terminals with globe in the Taskbar indicating it thinks it has an Internet connection? Yes Try Internet Explorer (No Add-ons) under Programs > Accessories > System Tools. Ah ok, will try that Uninstall any security software that includes a firewall. Will speak to him about this and see if he's happy about it Under Internet Options > Advanced, reset Internet Explorer. Thats a new one to me - thanks! Will give that a go Can any other program access the Internet? ?Ping, nslookup but oddly dos's ftp couldn't connect to my website Check the hosts file. Ok Run an virus scan for evidence of a DNS changer. AV is out of date so won't pickup anything

Will try those that I hadn't thought of / known of - thanks.

[#4]

If the security software has not been able to update itself then it's not just an Internet Explorer issue.  In which case the most likely cause of the problem is a malfunctioning firewall in the security software or a malfunctioning computer virus that had intended to subvert the internet connection but blocked it completely.

[#5]

The security software (PC Tools) is a trial version thats out of date so in truth I've no idea if its the internet OR the OOD version that has stopped it updating.
I will try to get back to him in the next few days.

[#6]

Running with out-of-date security software is asking to get a computer virus.  A useful tool that scans very quickly is TDSSKiller http://support.kaspersky.com/faq/?qid=208283363 ; Before you run it, click change parameters and select the Detect TDLFS file system option.  The TDSS family like to subvert your DNS and are often well-concealed.