Event log filling with these errors

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Error 1. Event Type: Warning
Event Source: Srv
Event Category: None
Event ID: 2021
Date: 20/09/2006
Time: 11:32:55
User: N/A
Computer: SERVER
Description:
The server was unable to allocate a work item 1 times in the last 60 seconds.
error 2 (very frequent)
Event Type: Error
Event Source: NETLOGON
Event Category: None
Event ID: 5774
Date: 20/09/2006
Time: 11:32:43
User: N/A
Computer: SERVER
Description:
Registration of the DNS record 'a988e4e2-ec64-4c62-9ae8-979f96e9f2f2._msdcs*********roup.com. 600 IN CNAME server.gra*******roup.com.' failed with the following error:
DNS operation refused.
Error 3
Event Type: Error
Event Source: w32time
Event Category: None
Event ID: 62
Date: 20/09/2006
Time: 08:49:41
User: N/A
Computer: SERVER
Description:
This Machine is a PDC of the domain at the root of the forest. Configure to sync from External time source using the net command, 'net time /setsntp:<server name>'.

Can anyone help, i am running a windows 2000 server with exchange 5.5 also running on it. Thank you in advance.