Adblockplus totally messed up my browsing, blocked Internet connectivity and crashed the N900 by repetition. I tried the workaround promoted somewhere (editing pref.js, adding a working patterns.ini) to no avail. I uninstalled it and things got back to normal.
I love Adblockplus but the side effects are too harsh. The usefulness of this tool will likely have me search for other workarounds to fix it, but I don't believe the app has a place in the repository.