I don't use the software updater, so I didn't install it on my custom install, you can remove it completely.
XP - Add Remove programs, select 'avast! Anti-Virus,' click the Change/Remove button and select Change, click next and in the next window you can uncheck the Software Updater option.
Vista, win7 - Control Panel, Programs & Features, uninstall a program, select 'avast! Anti-Virus,' click the Uninstall/Change and select Repair, click next and follow.
You may need to reboot after the change.
That said, can't you simply have the software updater not monitor flash as a temporary measure, which should be resolved when the database catches up to the latest release.