Can I stop "SYN Flood ***(from Outbound WAN"?

[Old Dog 62]

I have an SMC Barricade model SMC7008ABR router. When checking the logs I periodically get warnings of “**SYN Flood to Host** 192.168.2.xxx, xxxx->> xxx.xxx.xxx.xx, xxxx (from WAN Outbound)”. The originating address is from 2 of the computers on my home network. The destination IP changes as shown from an excerpt of my router log.

02/03/2008 12:16:09 192.168.2.101 login success
02/03/2008 10:51:21 NTP Date/Time updated
02/03/2008 04:51:21 NTP Date/Time updated
02/02/2008 22:51:21 NTP Date/Time updated
02/02/2008 20:12:34 **SYN Flood to Host** 192.168.2.101, 3350->> 66.165.186.98, 80 (from WAN Outbound)
02/02/2008 20:05:10 **SYN Flood to Host** 192.168.2.101, 4725->> 208.122.223.21, 80 (from WAN Outbound)
02/02/2008 19:29:34 **SYN Flood to Host** 192.168.2.101, 4941->> 213.189.18.86, 80 (from WAN Outbound)

My concern is the “from OUTBOUND WAN”, I assume this means that I have out going traffic that hopefully the router is stopping. How can I locate and kill the cause of this message?

I regularly use Sypbot, Adaware SE+, and AVG to control the bad thing on both machines and the router’s firewall is on. The OSs are W2K Pro & Vista Home Premium. Browsers are Firefox, set to clear everything on close, and MS IE used mainly on the Vista machine.

My searches have provided a lot of info on what a “SYN Flood” is but I have been unable to find that anything that tells me how to clean the cause from my systems. Let know what more information is needed or if any one can shed light on a “cure” for this.

Old Dog in need of new tricks!