OK, so there are 2 different problems.

  1. WebShield and the Ovlerapped I/O in Progress error
  2. NNTP related issues.

For 1., there’s another thread very similar to this one (but no solution yet): http://forum.avast.com/index.php?topic=11364.0
What router do you have, exactly? Is the problem perfectly reproducible? Have you experienced similar problem on any other web page?

For 2., the tray icon is indeed avast filtering the NNTP traffic. The strange part is that you’re saying that the newsreader crawls at 0kbps. So we’d need more info on this one too. What newsreader are you using? On which OS? Is the problem reproducible?

Thanks
Vlk