Old and slow usually does not cause freezes, but torrent users are often infected with viruses or malware so make sure you have good protection installed. Another common issue is bad memory, so check that also.
A program itself will not work because when Windows freezes so do your programs. However. . .There is a combination software/hardware solution called a watchdog timer. They include a card you install that will reset your PC if the software does not regularly reset a timer. They are generally used on specialized PCs that control systems or automated equipment 24/7, but you can install them in any PC. One source is here
, but you can find others by searching.