Ensure you have the complete set (e.g., parts 0001 through wherever the sequence ends) in one directory. Use a Compatible Extractor:
: A free, open-source alternative. You only need to open the first file in the sequence, and 7-Zip will automatically detect the others. Download File 570.part0001.rar
This usually means one of the parts is corrupted. You can try the WinRAR Repair Tool to fix minor header issues. Ensure you have the complete set (e