Incidentally, reinstalling also solved the problems I was having with Windows Security Centre whereby Avast was recognised in both Malware categories but it's status wasn't reported correctly. Just previous to uninstalling and reinstalling the application, I had tried the "delete the repository at \system32\wbem\repository" troubleshooting step without any success - the repository was just recreated with the same misinformation.
however, upon reinstalling later that day, it is now working correctly.