I was having the same problem and just found out from the google chrome help forum that it is Webrep causing the issue. I also use IE9 and it doesn't seem to affect that. Anyone know why this happens and if avast are likely to fix it? Only ask because I would rather use chrome than IE9 and don't want to keep switching Webrep off.
I have no problem with Webrep with Google Chrome.
E5200 2.5GHZ, 4GB RAM, 320GB HD, Windows 7 Home Premium 64bit, avast! V9.0 Free, IE10
P4 2.8GHZ, 1.5GB RAM, 40GB HD, XP Pro SP3 32bit, avast! V9.0 Free, Google Chrome
with hpHosts, MVPS HOSTS files, SpeedFan, WinPatrol PLUS