Hey Craftec,
It’s radicalb21. I just did a lookup and it comes back to avast. Here is the information i got back from the lookup. here it is:

rs1.avast.com = [ 66.98.166.72 ]

Registrant:
Alwil Software AS AVAST2-DOM
Prubezna 76
Praha 10 Czech republic 11000
CZ
Domain Name: AVAST.COM
Administrative Contact Technical Contact:
Baudis Pavel baudis@ASW.CZ

    Alwil software 
    Prubezna 76 
    Praha 10 110 00 
    CZ 
    420 2 74005 666 fax: 420 2 74005 555 
 Record expires on 05-Oct-2005. 
 Record created on 06-Oct-1997. 
 Database last updated on 25-Jun-2004 18: 30: 27 EDT. 
 Domain servers in listed order: 
 CAT.ASW.CZ 
 NS1.AVAST.COM                67.15.0.83 
 SNS.NEXTRA.CZ 

An RST Attack is using a TCP Ip protocol RST attack on RFC-based TCP stacks
Public Advisory

Attack ID: CPAI-2004-17
Last Update: 21-Apr-2004
Category: RST attack on RFC-based TCP stacks
Vulnerable Systems: Any operating system or software that has implemented TCP based on RFC 793 and RFC 1323
Source:
Updated
22-Apr-04 NISCC
CAN-2004-0230
Description: A security vulnerability has been discovered in the implementation of TCP designed in accordance with the TCP RFC. The vulnerability allows a malicious user to send a specially crafted TCP packet with a RST or SYN flag inside an existing connection and cause its termination.
Severity: High
Read the FULL ADVISORY and SOLUTION
(ID and Password Required)
Updated
22-Apr-04

Hope this helps my friend. I would in the mean time blck access to from that IP until we hear something from AVAST guru’s.