Hi, I don't know if this is the exact same bug that I encountered, but it sounds similar in nature. Where I saw it was after a scale change event and I wanted to toggle visibility. The bug was introduced in ver 2.6 and is still in the 2.8 version. I am told it has been fixed for the next release.
I had to add "navigationMode" to my map object:
var map = new esri.Map('mapDiv', {
displayGraphicsOnPan: !dojo.isIE,
lods: lods,
extent: startExtent,
slider: false,
nav: true,
navigationMode: 'classic', // Fixes an ESRI bug introduced at 2.6, toggling layers on/off at a scale change.
logo: true
});
Good luck,
Don