SYN FLOOD to Avast czech republic

I get, with irregular intervals, messages from my firewall with the next content:

No. Time Source IP Destination IP Note
1|07/18/2012 11:35:52 |192.168.1.33:3471 |62.109.145.78:80 |ATTACK
syn flood TCP

End of Alert

Is 62.109.145.78 an Avast website address in east Europe (Czech Republic)?
And why the syn flood to this address ?