Windows XP professional, SP 3 with all the latest updates, two hard drives.

Everything was working fine. Just two days ago i started getting the

message untitled4.jpg

it pops out every few minutes. I delete it comes back. Windows defragment disk could not have access to the disk. It's been like this for this for the past two days. I reformatted the disk. The same thing. This is all I have on the disk

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And then I got this message out of the blue in the middle of the screen

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I scanned the disk for errors Non. What is exactly the problem and how to fix it.