IP address conflicts

We are getting 5 to 10 IP address conflicts on our network every day. When I check the DHCP pool I have about 7 entries that say BAD ADDRESS with some wacky MIC addresses that I can’t trace. After I delete these, the conflicts stop for awhile, but they invariable come back the next day. I’m running a pool of 120 addresses, on NT 4 sp6a. Please help!!!