Well, my first question I posted here was about DHCP. I had a user that could not get an ip with dhcp on his home computer.
The problem seemed so simple! But after 1 day and a half of frustrating work, after trying everything (use 3 kinds of wireless adapters, using wired adapter, fixing winsock, reinstalling TCP/IP, repairing windows, restoring to a previous date) I examnined closely program files, and found out that the user had Comodo Security that blocked most of his ports.
He did an unistall the wrong way and got it off the Add/Remove programs list, startup, etc, but the process blocking the ports was still running!
I solved it by restoring Comodo, and unblocking the ports.
But guess what? I performed a full format anyway the next week because the computer was running slow after trying everything and going through repair and restore.
At least I was very happy that I found the problem :P