asterisk users - Apr 2007 - app_rxfax produces "RTP: Received packet with bad UDP checksum"

I have tried to set up app_rxfax to receive faxes over IP.  I realise 
there are mixed stories about how reliable this is at the best of times, 
but at this point all I'm after is some guidance in interpreting the log 
below.  What does "RTP: Received packet with bad UDP checksum"
suggest?
  Here is the full log:

     -- Executing SetVar("SIP/0892130888-b27c", 
"LOCALSTATIONID=+61-8-9213-0889") in new stack
     -- Executing SetVar("SIP/0892130888-b27c",
"FAXRECIPIENT=terminus")
in new stack
     -- Executing Goto("SIP/0892130888-b27c", "faxrecv|s|1")
in new stack
     -- Goto (faxrecv,s,1)
     -- Executing AGI("SIP/0892130888-b27c",
"receive_fax|receive") in
new stack
     -- Launched AGI Script /usr/share/asterisk/agi-bin/receive_fax
     -- AGI Script receive_fax completed, returning 0
Apr 23 17:30:25 NOTICE[4704]: rtp.c:435 ast_rtp_read: RTP: Received 
packet with bad UDP checksum
Apr 23 17:30:25 WARNING[4704]: pbx.c:1949 ast_pbx_run: Timeout, but no 
rule 't' in context 'faxrecv'
     -- Executing SetVar("SIP/0892130888-b27c", 
"MY_CALLERIDNUM=0894570732") in new stack
     -- Executing DeadAGI("SIP/0892130888-b27c",
"receive_fax|deliver")
in new stack
     -- Launched AGI Script /usr/share/asterisk/agi-bin/receive_fax
     -- AGI Script receive_fax completed, returning 0

Thanks!

-- 
Jeremy Malcolm LLB (Hons) B Com
Internet and Open Source lawyer, IT consultant, actor
host -t NAPTR 1.0.8.0.3.1.2.9.8.1.6.e164.org|awk -F! '{print $3}'

I have tried to set up app_rxfax to receive faxes over IP.  I realise 
there are mixed stories about how reliable this is at the best of times, 
but at this point all I'm after is some guidance in interpreting the log 
below.  What does "RTP: Received packet with bad UDP checksum"
suggest?
  Here is the full log:

     -- Executing SetVar("SIP/0892130888-b27c", 
"LOCALSTATIONID=+61-8-9213-0889") in new stack
     -- Executing SetVar("SIP/0892130888-b27c",
"FAXRECIPIENT=terminus")
in new stack
     -- Executing Goto("SIP/0892130888-b27c", "faxrecv|s|1")
in new stack
     -- Goto (faxrecv,s,1)
     -- Executing AGI("SIP/0892130888-b27c",
"receive_fax|receive") in
new stack
     -- Launched AGI Script /usr/share/asterisk/agi-bin/receive_fax
     -- AGI Script receive_fax completed, returning 0
Apr 23 17:30:25 NOTICE[4704]: rtp.c:435 ast_rtp_read: RTP: Received 
packet with bad UDP checksum
Apr 23 17:30:25 WARNING[4704]: pbx.c:1949 ast_pbx_run: Timeout, but no 
rule 't' in context 'faxrecv'
     -- Executing SetVar("SIP/0892130888-b27c", 
"MY_CALLERIDNUM=0894570732") in new stack
     -- Executing DeadAGI("SIP/0892130888-b27c",
"receive_fax|deliver")
in new stack
     -- Launched AGI Script /usr/share/asterisk/agi-bin/receive_fax
     -- AGI Script receive_fax completed, returning 0

Thanks!

-- 
Jeremy Malcolm LLB (Hons) B Com
Internet and Open Source lawyer, IT consultant, actor
host -t NAPTR 1.0.8.0.3.1.2.9.8.1.6.e164.org|awk -F! '{print $3}'