2e66a53a_cks___Aggressive_Virus_Defense__2
[Denial of Service] SYN Flood TCP packet with SYN flag (and probably spoofed IP address) received, TCP packet with SYN and ACK flags sent, then … nothing. Do this enough times, and the server cannot accept requests until the spurious connections time out. [2] 
Decrease timeout Increase connections Your IDS probably logs SYN flood attacks Your IPS / firewall should be catching SYN flood attacks Install patches
Attacks | Aggressive Virus Defense
2