OK, presumable these reported that they were clear.
What errors/problems were you getting that you tried avg (possibly related to internet connections) ?
What happens when you do a manual update of the virus definitions from the avastUI, Maintenance, Update are there any other errors other than the Cannot Connect To Server Error ?
I just wonder if when installing avast there may have been remnants of a previous AV that it didn't install correctly, so you may want to consider a clean reinstall of avast not you have confirmed any possible remnants have gone.
- Download the latest version of avast, 8.0.1483
http://files.avast.com/iavs5x/avast_free_antivirus_setup.exe and save it to your HDD, somewhere you can find it again (if you didn't save your last download). Use that when you reinstall.
- Download the avast! Uninstall Utility, aswClear.exe
find it here and save it to your HDD (it has uninstall tools for all versions).
- 1. Now uninstall avast! - using add remove programs, if you can't do that start from the next step, reboot.
- 2. run the avast! Uninstall Utility, it will request it be run from safe mode (and will handle the boot into safe mode), first for 7.x if previously installed and then for 8.0, once complete reboot into normal mode.
- 3. install the latest version, reboot.