When using IAR debug, the software crashed. After forcibly closing it, I opened it again and found that the emulator could no longer be recognized. It prompted "fatal error: failed to re-initialize session aborted!". Then I found that the FET430UIF-CDC device was no longer displayed in the XP system device manager, but there was still a system prompt sound when I unplugged it; I tried to restart the software and the system, but it didn't work. Some people on the Internet gave the solution: restart the system and reinstall the driver. But I didn't try this, and chose to refresh the firmware. Downgraded in the win8.1 system (strangely, the device manager at this time showed the CDC version of the emulator. I specially installed the latest version of IAR6.3 in the win8.1 system to verify whether it can be used, but it didn't work). It may be a software compatibility issue. When the downgrade was halfway through, the command line of the downgrade software kept prompting to plug and unplug the emulator, so the process was stopped. At this time, the status was that the VCP version of the firmware was being installed, and both status lights were off. After uninstalling the simulator driver in the system, I installed the VCP version of the driver, and then took it to the system with CCS6.1 to perform simulation. CCS prompted me to upgrade the firmware. After confirming, I erased the new firmware. At this point, the indicator light started to flash normally. I think it should be OK.