Unfortunately, the producer has removed "Sony PSP System Software 6.31" from its servers. However, you can download a newer firmware version compatible with the same gaming console, namely: Sony PlayStation Portable Firmware 6.60
It is highly recommended to always use the most recent driver version available.
Try to set a system restore point before installing a device driver. This will help if you installed an incorrect or mismatched driver. Problems can arise when your hardware device is too old or not supported any longer.