Hello all, I am experiencing a problem with my computer which I believe is being caused by one of my data hard drives Before I go into details here is my current hardware: Q6600 3.0GHZ GIGABYTE EP45-DS3R 6GB PC2 6400 800mhz (2x 2gb/2x 1gb) Nvidia GTX 275 896mb Onboard soundcard Windows 7 x64 Jeantech 1000W PSU Operating system is on 500GB drive ++ two 1TB data drives (2.5TB total storage) The problem: Upon accessing certain files in one of my 1TB drives, I hear a distictive "click/lockup/halt" sound and then the entire system crashes (first the drive will become inaccessible, then windows explorer will crash, followed by the mouse and eventually a BSOD after a minute) My sixth sense is telling me there must be certain portions of this drive which are extremely corrupted/malfunctioning - an uneducated guess as to what could be happening. Possible causes: I rarely defragment (once a year?) and I am always working with/shifting around massive uncompressed video files (30GB+) I haven't had to format my operating system for a few years, so could there be corrupted registry files? I haven't used any registry clean up/checking software PSU issue? Bear in mind the computer has operated flawlessly for the past year and the crash appears to coincide with opening/accessing certain files Generic hardware malfunction Things I've tried: Error checking tool (this process itself crashes the "faulty" 1TB drive after about 10 seconds causing the system to crash completely) Defragmenting "faulty" 1TB drive - no impact? Maybe I should try another defragmenter... Error checking tool for C: drive (500gb/OS drive, pre-boot) nothing to report no impact Things I haven't tried yet: Defragment other drives (OS drive/other 1TB storage drive) Error checking tool for other 1TB storage drive Check for loose cables inside system - (I doubt this can be the cause of my problem) Try different defragmenting software from the windows one Format OS Run antivirus software Use registry clean up software Other notes: Since the problem began (about one week ago) the system fails to boot 1/5 times - cannot find "HDD" message at "verifying dmi pool data" screen.... but the OS is on my 500GB drive which doesn't appear to cause any problems? I have tried to go into as much detail as possible if you have any suggestions they will be much appreciated!