like the last two posts say, dont use a task killer, they cause more harm than good. if you must use watchdog (free in the market)
ok so we need more info, your rooted. what guide did you follow.
power off. then hold down volume down button when powering on - write down everything you see here.
then do you have a custom recovery? did you flash a custom rom? did you do a full wipe?
these are all things we need to know if you want useful help