What if you just stop the web shield for 10 minutes ?
You could also try adding the URL to the avastUI, Real-time Shields, Web Shield, Exclusions.

I see from your signature that you are still using avast 5.1, the latest release is 6.0.1091. Or you could try the pre-release version of avast 6.0.1119, if you are happy to try a pre-release build, it is quite stable. For more info and download links http://forum.avast.com/index.php?topic=77580.0.

The reason I suggest it is there is little value in trying to chase down a problem in an old version.