Hi PushkarMy 1 TB is 3 months old from samsung
Also received 500 GB replacement HDD from WD recently
Your HDD's may not be failing if they are new. Could be some corrupted data that needs to be removed (or umpteen other things

)
I had a problem with one of my disks a couple of months ago and it turned out to be the SATA cable so I bought another one (I think it was £1 for 2 cables here in the UK) and as soon as I fitted it the problem stopped.
You could open your case and make sure all your cables are plugged in correctly and haven't worked loose and whilst you are doing that you could make sure your memory stick(s) are embedded properly as they can cause problems. If you have a spare SATA cable you could also try fitting it in place of your current one.
both seams new & no prob in windows scan disk
Do you experience any of these file stalling type problems when using Windows?
Also downloaded PC LOS 2010 beta from Opera as mentioned earlier will clean install on another partition
Okay - check your sata cables and memory sticks. (Replace sata cable(s) if you have spare handy)
Then see if the problems persist.
You could also install PCLOS 2010 beta1 into a clean fresh partition and see if any file/disk related problems occur - if they do we can then try some other things
BTW Can I ask why you had to have a replacement disk from WD - were you having problems with that one? If so, what type of problems? Were they similar to whats happening now?ALSO: do these problems happen on both disks or just one of them?