You say you have checked all the settings, but there appeared to be a discontinuity from FF2 & 3beta in that plug-ins work differently and are not automatically suggested for update. I noticed this with the colour profile was 8989 or whatever but is now called 'Colour management 0.4' and needs setting. Likewise the 'add-block plus' offers hand-weeding facility, which is why I thought you might have pulled out a flower by mistake.

So check any add-ons and plug-ins? CCleaner seems to be a general cleaner like our MacScan and I presume likewise marks up borderline items for you to confirm delete?