Active Directory and DNS

I am having problems with my DNS It appears to be working for a while and then I start to receive errors. I have one domain 3 windows 2000 servers Active Directory and intergraded DNS. In event id the errors I see are 3000,4011,6702. I have lookedup the errors and followed the work arounds I have also down loaded the latest service Pac and critical updates. I still seem to be having problems. I also think I am having problems with replication. Through out the day there may be several pc’sthat freeze and when the user tries to log back in it says it can not find the user. I do not however see and errors pertaining to replication however if i force a replication then the users can log back in.

Help!