Why does this keep happening to me

its the second time in two months this has happened

my external hard drive which is a seagate 80gig firewire gives me the error message 'g drive is unreadable and corrupted'

i have no idea why this is happening, i'm running chkdsk now on my c drive and the g,

my music pc is not connected to the internet so i dont think it could be a virus unless something got copied over when i was transfaring data or samples between the two

lucky i can get the data back using a recovery programe but its a pain in the ass cause the files come back in a random order and sorting them takes ages

I want to know whats causing this cause i'm rightly pissed