I recently installed Avast 6.0.1000 and chose custom installation. I chose NOT to install the Webrep toolbar as part of the installation. Regardless, the Webrep toolbar was apparently installed in Internet Explorer 64-bit. It didn't seem to install in any of my other browsers (Firefox, Chrome, IE 32-bit). It seems like an installation bug.
Although I can disable the toolbar in IE 64-bit, I can't seem to find any way to totally remove or delete the toolbar from the system. It doesn't show up individually in the list of installed programs in Windows. I also can't find anything in the Avast UI to remove it and can't seem to find a way to remove it using any of the menus or options in Internet Explorer itself.