I've experienced similar blocks from hack/spitMS crapVista's protection software that is more than just an annoyance. So I change the settings if I can find them.
The AVG ver8 doesn't announce any real threats, so I disregard the other warnings.
I suspect that the "triggers" for these events aren't necessarily eBay's crap, but different types of (unknown to me) provoking tools used by the advertisers in the numerous flash/other animated BS ads, or "enhancement tools" used by the eBay sellers to make their auction listings unique/special (all useless crap to me).
When I encounter these useless "features" I generally just look for another source that wants to sell products, not impress potential buyers with stuff intended to amaze or delight 14 year olds.
Any time that I've used Norton or McAfee products, I was dissatisfied. They appear to be unnecessarily complicated and/or overly annoying.