[Q] help? strange corrupted file/folder maybe

okay, I upgrade my n70f00 from ics stock to jb stock then root with philz kernel. everything went fine. then I notice my phone a bit slow, memory almost full (left less then 100mb out of 800mb) and everytime I boot I get 'android is upgrading, app statting.." notification. i want to reset, but when I do backup with cmw always fail (never backup before). do some this and that, i found that i can't access folder '\data\lost&found'. each time I click that folder using any rooted explorer I have the phone restart. I search and found sgs tools app that can delete corrupted media file, and it did. but I still can access '\data\lost&found' folder (keep restarting).

any idea at all?

thanks in advance..