DHCP server hang up and not responding

Hi,

I have log time DHCP server on W2K8 R2 for 3000 wireless users. Now i have problem with this server - log contained many same DHCP renew requests (about 250 per second):

11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
11,03/17/11,15:05:41,Renew,172.18.161.221,Monca-PC.eduroam,0025D38240E4,,1784160628,0,,,
02,03/17/11,15:05:41,Audit Log Paused,,,,,0,6,,,

and server not respond for any other user.

How resolve this problem ?

Thanks,

Ladislav