Originally, my C drive had nearly 8GB of space. After installing an operating system and some software, there was still over 3GB left. However, I recently discovered that there is now only a little over 1GB remaining. At first, I thought it might be due to some junk files generated by the system, but after optimization, I found that the disk space hadn't increased much. Upon checking the C drive, I noticed that the folder "Documents and Settings\All Users\Application Data\thunder_vod_cache" was almost 2GB in size. I initially thought it was some kind of system file. In reality, it was just the cache file for Thunder (Xunlei) Video Player, so I deleted it right away, and my disk space returned. I wonder if anyone else has encountered a similar situation.