I just had the weirdest issue. I'm using:
- Avast! Free Antivirus version 6.0.1203
- Virus definitions version 110718-1
- Windows 7 Professional 64-bit
- Firefox 3.6.18
I'm a sysadmin and was using Wireshark (a packet sniffer/decoder) to diagnose another application. But when I looked at the results, I noticed that I was seeing a flood of packets to and from a site I visit regularly, dreamwidth.org, all containing
HTTP 400 Bad Request responses.
Further investigation revealed that my computer was echoing back the contents of these responses to dreamwidth.org, which then responded with another HTTP 400 Bad Request response. I verified this was a new response because the Date header would differ depending on the time.
Further investigation revealed
AvastSvc.exe to be the cause of these packets, as shown in this image:
http://neo.theblob.org/avast-weirdness.png . For some reason, Avast was taking part in an infinite loop between Dreamwidth and my computer. I have no idea why.
I managed to fix the problem by temporarily turning off the
Web Shield component, which stopped the flood of packets. It seemed to break the infinite loop because turning it back on didn't resume the flood.
I have no idea when the flood started or why it would have started, so I'm hoping that posting here might help me find some answers. It seems like a bug in Avast!, at least.
(If any people at Avast! would like the capture file I saved with these packets, let me know and I can supply it.)