Are adds fighting back?
I've noticed a strange thing since installing W7. -- Obviously needing a reinstall of Adblock plus.
The Adblock plus seems to work the same, but often - increasingly often - the adds are defeating the system.
Now and then I see a flicker of the [block] tab, but it's ethereal and often gone before the cursor is upon it. If I can catch it, it works. There is no right click menu option on these particular determined ones.