Yes, AdBlock Plus has some quirks that badly affect microB, specially 1.0.2 version which I found almost impossible to remove by conventional means.

rm -rf ~/.mozilla/microb will remove everything added to microB in the user space, basically reverting it to what it was when you first started it (you'll loose all the settings, bookmarks, passwords...) so you'll be starting with a clean state (unless you installed some extension that stores itself outside of the user space).