Using The O1 with V10c stock ROM. Giving me lotsa headache with random SD unmount/freeze/restart.

Change from stock SD card to Kingston Class 4 8GB, still having the same problem. Finally upgraded to V10e using the supplied LG software, now seems don't have such problem anymore. After the upgrade, all the previous apps was still intact, is this normal?

However, I do feel significant lag after I upgraded to V10e.. anybody having the same issue?

Want to ask if we downgrade to V10a or V10c, our NDrive app will still be around? Can't seems to find NDrive.apk anywhere in the SD card...

Any advice?