adb-tooltip: how to get rid of it?

Hello, I’ve got a bizarre problem on one of my blogs. This strange CSS overlay is popping up on one of the pages. About half way down, you’ll see that little tooltip that reads:

Person William Golding
Right click for SmartMenu shortcuts

I have googled for “SmartMenu” and googled the source, which is:

<div id="adb-tooltip" style="z-index: 1000; position: absolute; display: block; left: 122px; top: 1053px;">
<div style="border: 5px solid #c4dae8; margin: 0px; text-transform: uppercase; font-family: arial; font-style: normal; font-variant: normal; font-weight: bold; font-size: 11px; font-size-adjust: none; font-stretch: normal; -x-system-font: none; line-height: 13px; background-color: white; color: #333333;">
<div style="border: 1px solid #78b3d9; padding: 5px; text-align: left;">
<div>Person<span style="color: #006699;"> William Golding</span></div>
<div style="text-transform: none; color: #999999; line-height: 14px;">Right click for SmartMenu shortcuts</div>

I can’t seem to find anything about adb-tooltip, or how it got there. I’ve done the obvious things like disabled all plugins, and retrograded the theme back to the Default, and still it shows up! This has baffled me.

Any ideas?