Wow! What a lot of response - thanks! I'm back now. Sorry, I was away most of the day, and didn't expect such kindness.
DavidR, I think you may have given me my answer. I do use the Firefox Speed Dial extension, and have quite a few sites bookmarked that way. I'm a bookish sort, and had thought it sounded like a site I would like. So when I looked at the "shopping" tab of my Speed Dial, there it was. I deleted it, and have high hopes I won't get the same message tomorrow.
Pondus, I'll check out the ATF cleaner, too. Thanks for the suggestion.
And thanks again to all of you, for your help.