Hi all sifus, hope some one could help me with this problem that bothering me for long time already...
I have data lost problem quite frequently. Pictures taken with the camera gone after phone reboot, many of them ended up in the LOST.DIR folder. Did some test by saving some JPG file from browser, move it to external MicroSD card, also gone after phone reboot. I tried to fix this by backing up everything from the card, then do a full format (slow format) on my PC, then copy everything back to the card. It work without problem for a about a week.
Today, I just lost another MP4 file (150MB) that I copied onto it a day ago. Found it inside LOST.DIR again.
I simply power off the phone, take out the battery and install back after 2-3 seconds, then later I only realized the video file is gone.
Anyway, I just tried backup everything again then format the card from within the phone. I will see if this solve the problem.
What I want to know is, does this caused by Android filesystem or the card physically having problem?
If I remember it correctly, I don't have this problem initially. This make me wonder if it is 4.1.1 firmware causing this problem? Anyone having this filesystem problem as well?
My phone currently all stock, in official 4.1.1 and I never root it before.
Once again, thank you in advance!

Nothing wrong with firmware that's for sure , did u set or install any apps that might have caused this ? To be frank , 1st time hearing phone auto delete files . Is your unit SME unit ?