I had a problem with a computer where after cleaning off a virus there was no internet access, and no network connectivity at all. When I tried to ping localhost, it said:
Unable to contact IP driver, error code 2.
When I tried to do ipconfig, I got:
An internal error occurred: The request is not supported.
Additional information: Unable to query host name.
After some digging through event logs and Google, I found the problem. The virus had damaged some drivers, specifically c:\windows\system32\drivers\IPSec.sys. That file was completely missing, so when I replaced it and rebooted everything started working again.