This is definitely an unusual concern! I researched and found no related concerns. I'm glad the device is up-to-date! I recommend trying another SD card, as the card maybe unseating itself. If you still see this happening, a hard reset (http://tinyurl.com/9tkhthg) may be necessary to resolve! Keep me posted!
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We have a non-smartphone the Samsung Reality/u370.
It has two different bugs whose work-arounds I thought might be applicable to your situation on your LG Extravert.
One bug is that every now and then it'll reset the wallpaper to the phone's pre-loaded wallpaper. The workaround is to move the customer's custom wallpaper off of the memory card and into the phone's internal memory.
The second bug can occur when a person listens to music while headphones are plugged in to the phone. After awhile, when the bug occurs then the phone is suddenly unable to read any of the customer's files stored on the memory card. Powering the phone off and then back on causes the phone to read the memory card just fine again.
LG has a forum for customers to report issues. Maybe it might be worthwhile to report this because LG employees read that forum and sometimes answer questions, complaints, and concerns.