Since last week, the smartphone I usually use (Kyocera WX10K/Android 4.2.2) has been acting up, and has been on the verge of dying at any moment. By the way, the other tablet I'm using (Nexus 7/Android 5.0.2) seems to be fine so far, probably because it's the latest OS with Android bugs fixed. Now, in that situation, when you open the file gallery on your smartphone or connect your PC to SlimPort, your smartphone freezes, and it is a tragic phenomenon that cannot be repaired even if you force close it and restart it. After doing some research, I found that most of the 8GB internal memory (about 7.5GB) was taken up by thumbnail files (.thumbnails), and the direct cause was that there was almost no free space left. By the way, it doesn't contain much image, video, or audio data, so I think it's unusual for such a huge thumbnail file to be created. (Android or app bug) Therefore, today I would like to report that I succeeded in getting out of this predicament using the method below. If you are having trouble with a similar phenomenon, why not try it?