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I had an XP System and I installed Windows 7 on another Hard Disk so now I have a dual boot. However, when I boot windows 7, the hard disk where XP is installed does not always show up.

This started after few weeks where everything worked fine.

So the XP disk doesn't show in explorer on Windows 7, and in Disk Management Utility it is marked as Unallocated. When I reorder HDD boot order in the BIOS, it seems to fix it from time to time, for a few boots, but it gets back to that bad state after some short time.

I have a Gigabyte PS3 motherboard and I updated the IDE/Stata controllers for Windows 7. HDDs are Western Digital and Seagate. I checked the SATA cables; they are correctly plugged. The power supply is 700 Watts up and working.

Edit : Similar Issue here

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Does it boot windows xp from the first drive?If so the drive is fine, however if there is ahci enabled for the second drive and the first one is IDE you may encounter some problems on gigabyte motherboards. Try running it in compatible or enhanced sata mode and see if that fixes it.

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I do not understand all the notions but I'll try to educate myself on this. Yes it boots from xp from the fisrt drive. And yes, that drive is IDE and the other is SATA. I don't know at all if ahci is enabled (how to check that ?) and how to run in compatible/enhanced mode ? – Mika Jacobi May 23 '11 at 14:45
Check in the motherboard manual. It is controlled in the bios. – xciter May 23 '11 at 15:00
I checked and AHCI is turned off. This is pretty weird. All my HDDs are detected perfetcly on XP and I have unallocated problems on windows 7 – Mika Jacobi May 27 '11 at 18:45

Try running chkdsk

chkdsk /R C: (or whatever your XP drive letter is)

If you run the command in XP, it will run the next time you restart.

This will check the disk for bad blocks and will check the filesystem for errors.

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I'll try that... But it's funny that the disk gets recognized "randomly" – Mika Jacobi May 23 '11 at 14:46
I did that check. This was not the problem. – Mika Jacobi May 25 '11 at 12:36

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