I've not really paid much attention to it but for a few 'days' (certainly not very long) I've also been having the same problem with Adblock (ABP) not remembering what adverts or banners have previously been blocked, the only thing is though is that I don't use or have chrome installed, yes I did have to re-install some of my ad-ons after the last bout when I had problems with the latest update to Firefox so removed it and installed a previous version which had always worked ok, so thanks for the tip and I'll try disabling my add-ons to see if it solves the problem.
Edit:
I tried disabling most of my add-ons and that made no difference, so I then disabled Adblock, restarted the PC (because I like to) then re-enabled it and it is now it's much better, although sometimes I do initially see some banners but they fairly quickly disappear, so I think there is or at least was a Adblock glitch and possibly even 'deleting' it followed by re-installing it hopefully will cure the problem and take it back to how it used to be, I did notice that the auto-update feature on Adblock was enabled so again I don't know if it may have had a bad update, no-doubt time will tell.