Reviewing the results of the drive, I wouldn't be afraid to continue to use it. The error could be a number of things, the drive got to warm (check ventilation) clean the fans, etc. The hard drive didn't spin up fast enough ( firmware update addressed this). Too many hard restarts or abrupt shutdown from a power loss.
Could it be the errors found and repaired, after runnig the Seagate Diagnostic Tool? As I said, I performed the Seagate Test, and the hard drive didn't pass it (8 errors found). I chose the option fix them, ran the test again, and the disk passed it this time. BUT, the message said that the fix was not permanent and I should back up all my files, till I change the hard disk. That's why I asked for help, for buying a new disk.
Anyway, I have no reason not to trust you, and I will continue to use the computer. There are no freezing anymore, but who knows what is going to happen tomorrow! I would like to be prepared, in case the disc fail again. So, I think that I have to order a new disk, and keep it till I need it. I would like to order it online, but I don't know exactly what to ask.