We have had our network running with about 30 computers bought 5 years ago. Anyway, everything has been fine until today. We have two computers grabbing the same IP address from DHCP because they both have the same Mac address. The Mac address on both computers also is odd. It starts with 40 and the other 28 omputers bought at the same time start with 00. We have had to replace some hard drives and even mother boards over the years, but nothing in the past several months. I am really concerned that we have a hacker or virus running around, so any help/answers would be greatly appreciated. Thanks.