First if you have duplicate IP addresses, you need to be sure you're using DHCP so that your router can assign unique addresses. Then when your system can't find the PATH or IPCONFIG commands, that suggests a virus or corrupt system files, so I'd boot to Safe Mode and do a full system scan with the antivirus program. Then I'd go to an elevated command prompt and do SFC /Scannow to check for corrupt system files.

Good luck.