Windows 7: Partition Drives cannot be read

I have this Toshiba 640Gb HDD. I partitioned it into three logical drives. When I inserted the hdd in my xp, one drive cannot be read. Later when I used again the hdd in 7, it says that one of the drives needs to be formatted (the one that can't be read by xp). I did so but I noticed that the drive letter changed. Series of switching between the two OS, the drive's letter continues to change upon formatting. Then to arrange again the drive letters in their alpha list, I used Easeus Partition Master to change the letters of the partitions back as F, G, and H. After the process, when I inserted the hdd, it took significant amount of time for the drive to be read.

Is there any way to revert and restore the drive letters of the system? I've tried to restore from backup but to no avail.

Use Windows 7 DIsk Mgmt to create your partitions:

Partition or Volume - Delete
Partition or Volume - Create New

Do you have just that one hard drive in your Windows 7 system, and you're removing it and connecting it as a second hard drive in your WinXP system?

Or is it the second drive (external or internal?) and you're trying to use it as a second drive in both Windows 7 and WinXP?

Can you post a screenshot of DISKMGMT.MSC in both worlds, so we can see what's been allocated on each real hard drive and also each partition, as well as drive letters... for both OS's.

Please maximize the window from DISKMGMT first, and also spread the columns so that all of the text in each column is fully visible. Then take the screenshots in both versions of Windows.

Thanks.

@dsperber- it is simply an external hdd whcih serves as my backup storage for data and .tib files. what i did after the incident was to repartition the hdd into two and gave the partitions drive letters P & Q. that way up to now, no problems exist. and when i plug the device for another computer say an XP machine, the drive letters became F and G or H and I (depends on the system's recognition the first time you plug the device). it only changes when you inserted back the portable hdd and windows 7 prompts to reformat the drive and you do so giving it the letter after it's present drive letter (say it's J and you are prompted to format, it now becomes K)

i can get the screenshotsbut i'm running on xp now. no diskmgmt.

That's strange.
You should have it on XP.

1. Open your Start Menu
2. Right click on My Computer
3. Select Manage

This should start Computer Management.
Disk Management should be in the Storage section (Left column).

@lehnerus2000- the reason why i cannot access the function is because i'm using the computer of the office and we are only given restricted accounts.

Sorry.

If it's a work machine, can't your IT person (people) fix it for you?

Well, assigned drive letters have nothing to do with the physical hard drive itself and the partitions on it. Drive letters are assigned by the Windows operating system you're running on, depending on other partitions, devices, and drive letters already assigned.

You can use DISKMGMT in both WinXP and Windows 7 to change drive letters to whatever you want. So ideally, for convenience and understandability and consistency, you should obviously want to assign the same drive letters (say P and Q) to the partitions of the external drive in both Windows 7 and WinXP. And of course once you do this, those letters should stick as long as you keep the drive plugged in and don't remove it.

But if you unplug the drive and plug it back in, the reconnected partitions will once again get new dynamically assigned drive letters... normally the next available letters for that particular Windows OS. These letters will remain in effect as long as you don't unplug the drive.

So, as long as you don't manually change drive letters in a given Windows AFTER you plug the drive in and get letters dynamically assigned by Windows but rather just leave the letters that get assigned, and as long as you don't plug in any other device which also gets a dynamically assigned drive letter, you can count on the same drive letters getting assigned by that particular Windows each time.

But if your Windows 7 and WinXP systems have different "fixed" drive letters for your permanently connected devices, that means the "next available drive letter" is going to be different for your two Windows systems. And thus when you plug in the external drive, the dynamically assigned "next available" letters are guaranteed not to be the same for your Windows 7 vs. WinXP environment.

There's really no way to avoid this with removable devices and dynamically assigned drive letters.

It's in WinXP as well:

Start -> Run - diskmgmt.msc (just like in Windows 7)

Or, Start -> right-click on My Computer -> select Manage, and then select the "disk management" item down near the bottom-left in the Computer Management window presentation (again, just like in Windows 7).

The partition letters have to be higher then the last letter on either/or home or office machines...
In other words if F: is the 1st partition on the external but F: is in use at the office Windows will re-assign an unused letter to accomodate...

To prevent this select 3 letters all higher than ones in use on both machines....
Then in Disk Management assign each partition a Volume label and save...

Now you will be able to move from machine to machine and it will be the same on both.