Ok here is my problem. I am running Windows XP and IE6. I had
previously installed all the latest updates from the Windows Update
site for both. Recently I had a problem with IE (this third party
program I use wouldnt popup IE browsers like it used to) but
everything else was ok. So I tried doing an sfc /scannow but this
didn't solve it. So I tried doing an IE repair (from Add/Remove
Programs) and it didnt solve it. So I tried uninstalling IE and its
updates but then it wouldnt let me re-install IE (some error about IE6
not being XP-compatible!). Microsoft's support website suggested a
reinstall of XP (after trying several other methods including the ones
described). So I reinstalled XP but then I was not able to create a
new network connection. Microsoft's site advised me this can happen
when SP1 has been installed and advised me to delete two registry
keys. This solved the connection creation problem. I could now login
to my ISP (DSL provider) but not IE could not access any sites! But
Mozilla, Outlook Express, ICQ could. I ran the IE troubleshooting
program and it told me that my default gateway could not be pinged
(which is true - NO sites could be pinged) but yet everything else was
working perfectly except IE. I tried a proposed solution I read on a
website involving renaming CatRoot and restarting cryptserv (?) but
this didn't work.

Its not a proxy problem - my ISP does not require a proxy and there
are no proxies specified.  Its not an ISP problem - I also tried a
dialup connection from another ISP and had exactly the same problem.
When I try to reinstall IE, it installation program cannot connect to
the net (I assume it uses parts of IE?).  I suspect the initial
problem was this was from a poorly written old Windows 95 program that
deleted important things when I uninstalled it (but Im not sure)

Should you choose to accept this mission, the money will go to the
person who contributes the most pertinent information leading to a
final solution. Good luck!

Have you also tried to reset the TCP/IP on your computer.. 
the command is "netsh int ip reset c:\resetIP.txt" 
this needs to be done with the cable modem turned off and after this
is done you can shut down your computer and then turn on the modem and
then restart the computer.