The Less Detail... button just reduces the Detail in the On-Access Protection window not any scanner messages.
If the Web Shield settings are as this image, then you shouldn't be getting any messages ?
If it is and you are getting messages about web pages you are browsing, do you have multiple accounts on this computer and are you using one with admin privileges when modifying the settings ?
So there is a possibility your installation is somehow corrupt, a clean reinstall would probably be best.
Download the latest version of avast
http://www.avast.com/eng/download-avast-home.html and save it to your HDD, somewhere you can find it again. Use that when you reinstall. Ensure that you scroll down and select the avast direct download link for the English version and not Cnet as that is for an on-line installation (not what you want to do).
Download the avast! Uninstall Utility,
find it here and save it to your HDD.
- 1. Now uninstall (using add remove programs, if you can't do that start from the next step), reboot.
- 2. run the avast! Uninstall Utility, reboot. If step 1 failed it may be necessary to run this from safe mode, once complete reboot into normal mode.
- 3. install the latest version, reboot.