I was able to miraculously get rid of these bars under my task bar items. Note that I am *not* combining task bar entries - which may be necessary for this to work.
I manually got rid of the iconcache.db and associated files (see link below) and rebooted, and they were (miraculously) gone. At...
In case someone comes searching through here looking how to *get rid* of those bars - which I think may only be possible if you're NOT combining task bar icons - I successfully got rid of them after a reboot when I'd manually cleared the iconcache.db and associated iconcache files (e.g. Repair...