Freezing, disk i/o problems iMac I have a desktop iMac with Snow Leopard installed on it. Every few minutes, I get freezing and 

"kernel disk0s2: I/O Error"

in my console. I did some research, and found that my hard drive (a WD I had for only a year) may be failing. I've had failed hard drives before, and this doesn't seem like a failure because the hard drive is working quietly (there's no clicking noise at all even during the freezes) and I get a verified SMART status in Disk Utility. Are there any alternative theories to the kernel disk0s2: I/O Error in console or is it definitely an impending hard drive failure? Could it be due to overheating? WD drives get really hot. Any theories?
That is definitely the sign of some failure related to your HDD. The SMART status is not real helpful in many cases either; for instance if you have bad blocks it probably won't detect them. 

My recommendations would be back-up everything, then reformat the drive and see if the problem persists - or send it back to WD, since your HDD should be covered under warranty.