update to the latest version of Firefox , that is 3.6.13
and then click on the option of -- update the Add ons in the tools section .
the FF will check for updates to all of the extensions installed , including ABP.
restart FF , and then click on the ABP logo in the FF window and click on its preferences .
click on subscribe ,
and then click on the lists to which you want to subscribe to .
check now ..
it should be working ...
else try , turning ABP off and again on and again restarting FF .
it should for sure work now ..
if nothing then , uninstall it and re install the ABP extension ...