Exact same problem as GreggH and Gandalf here, too. I haven't rebooted my machine, but I have refreshed the Software Updater multiple times and it's still showing Flash ActiveX as being out of date when it isn't.
I think I know what the problem is though...Avast is looking for the wrong version number for the ActiveX version of Flash. If you check with Adobe's
own website, it lists the current version for IE/ActiveX as
12.0.0.38, whereas the Firefox version is .43 and Chrome is .41. Avast claims the "latest version" of the ActiveX is
also .43 when in fact it isn't, per Adobe.
EDIT: Should probably add that I'm on 7 x64 as well.