I have a mid-2010 27" iMac with an OWC Mercury Extreme Pro and factory 1TB WD Caviar Black (see signature for complete specifications). Recently, I noticed applications are hanging when first launched. I noticed it is specific to applications that rely on the User home directory located on the 1TB WD Caviar Black. It almost seemed the drive was taking extra time to resume from sleep. A reboot fixes the first instance, but it returned after some time. I have since did a PRAM reset and the problem appears fixed. I'm concerned there is a potential failure. I have Time Machine backups to a 3TB Time Capsule, so I'm protected. Should I be concerned of a drive failure?