Cyclic redundancy check (CRC) is a data transmission error detection function, which performs polynomial calculation on data and appends the obtained result to the back of the frame. Receiving devices also implement similar algorithms to ensure the correctness and integrity of data transmission. If the CRC check fails, the system will copy the data to the hard disk repeatedly, and it will fall into an infinite loop, resulting in the copy process not being completed. Solution: Note that some data have actually been copied to the hard disk in the above process, but when the CRC check of some data fails, the Windows copy command cannot skip these data and continue execution. When the operation cannot be completed, the system will delete the data that has been copied to the hard disk, resulting in a complete failure of copying. This problem can be solved if the wrong data can be skipped during the copying process. When we download files from the internet, the commonly used download tool is FlashGet. FlashGet can divide a file into several parts and download it at the same time, or it can carry out multiple download processes at the same time. Operating Steps: First, we set up a local site through IIS (Internet Information Service). If this component has not been installed, you need to click this component in Control Panel → Add/Remove Programs → Add/Remove Windows Components, select IIS, click Next, and insert the installation CD to complete the installation. Next, create a virtual directory whose address corresponds to the directory where the video file is located. Taking IIS5.0 of Windows 2000 as an example, the steps to create a virtual directory are as follows: (see attachment for an example) 1. Start IIS2 in Start Menu → Programs → Administrative Tools. Right-click the default website and select New → Virtual Directory; 3. Enter the directory name, assuming the name is YYFiles；; 4. Enter the directory path (the path should be the directory where your audio and video files are located). Don't change the rest, and click "Next" to finish. Then, start FlashGet, create a new download task, and enter "[URL] http://localhost/yyfiles/[/URL] hibernated. avi”。 So you can start multithreading download. When one of the processes reaches a certain progress, it encounters wrong data, and the speed gradually drops to zero, but the other parts still proceed as usual. After the rest is completed, it will be downloaded in several parts. In this way, except for the wrong data, the rest are downloaded to the hard disk. Finally, go to the download directory and put the file "impeded". avi.jc！” The name was changed to "impeded. Avi ",the copy process is complete. Although this is a bit complicated, it keeps my video file and doesn't need to be downloaded. It is suggested that the above processing methods can be used for audio-visual files, but not for some important files or software.