Agreed, more likely to be a system problem. Bad hard drive, bad power supply, bad memory, bad mobo, bad cpu, bad drivers, bad software (particularly anti-virus) - all of these can cause those issues.
Torrent downloads should never become corrupt really, as the BitTorrent protocol itself functions on check-sums that verify the content as it's downloaded, piece by piece. If you're getting corruption after downloading via BitTorrent, then you're either running failboats torrent client software, or your system is corrupting the data after the fact.
As mentioned, run a "force check" or similar in the torrent client if it has that facility available to re-verify the downloaded content.
You could also calculate the file checksum manually to check for authenticity using an application like
HashCalc. Set to calculate MD5 or SHA1 and check against the following:
prbf2_1.0.29.0_full.iso;
MD5: 64230b50da98c11c5750543646239839
SHA1: dad424af07024ddb8944731a6b01fcfad824cd38