Nice info from a co-worker:
Anytime you receive strange symptoms with TCP/IP including no browsing or pinging, misc errors, no browsing but able to ping, etc.... you can run WINSOCKFIX.EXE to correct this. This has happened to me several times after removing spyware from pc's.
http://support.microsoft.com/?kbid=811259&SD=tech
I thought this may be helpful. Here is a brief overview of what this article contains:
SYMPTOMS
When you try to release and renew the IP address using the Ipconfig program, you may receive the following error message:
An error occurred while renewing interface 'Internet': An operation was attempted on something that is not a socket.
When you start Internet Explorer, you may receive the following error message:
The page cannot be displayed
When you use your computer, you may receive the following error message:
Initialization function INITHELPERDLL in IPMONTR.DLL failed to start with error code 10107
Additionally, you may have no IP address or no Automatic Private IP Addressing (APIPA) address, and you may be receiving IP packets but not sending them.
