I have an external USB hard drive (Maxtor OneTouch 4, 1TB). It is formatted as NTFS (from factory). Lately, I found that xp didn't understand and mount it (not even in the disk manager). Sometimes a popup message tells that it is an unknown device, and similar. The drive worked with no problem previously.

I tried it to other usb ports, both directly on the computer's ports or through a D-LINK usb 7-port hub, with no better result. The drive's light remains ON but the drive doesn't appear anywhere.

However, I found that Linux had no problem to mount the drive, access the partition and the files inside. I checked this with the Ubuntu 9.10 live cd. This means that the hard drive has no problem, the partition table is good and the filesystem has no problem. [I was afraid that it was damaged, perhaps because of the power supply transformer that goes directly to the power, with no ON/OFF switch (sadly, most external drives don't have power switch). ]

- Can I suppose that there is a problem in the windows xp system (files or registry)?
- Any other idea?

Hardware specification:
M/B Asus P5B Deluxe Wifi
Intel Core2Duo E6600 (2.40GHz) / RAM 2GiB / 1 internal HD Seagate 320GB

Seems like a driver problem to me.

Did you try to manually add it from the DiskManagement tool on windows?

Not really. I didn't know that there is possible to do such non-automatic things under xp.
I'll try to do so.

I didn't find how to add any drive to the xp Disk Management. Is that really possible?

ok did you try

Start -> Control Panel -> Administrative tools -> Computer Management -> Disk Management

And you should see on the top right side Volume C: and in bottom right side Disk 0 and CD-ROM 0. If there are no driver issues, you should also see the new external hard drive, but it might not have a disk letter. So right click on it and choose "change drive letters and paths" and assign it a letter.

It should mount the drive. Make sure it doesn't ask for formatting the drive! if it does, don't do it.

Greetings

Alejandro

Thank you very much Alejandro.

Unfortunately, I was not clear in my first post. The problem is that the drive didn't appear in the right bottom section of the disk management screen. I didn't find any way to manually add any new drive in that section.
So, It might be a driver problem to solve.

By the way, I have 2 drives of this same model. This one showed this problem. The second one had no problem to connect. As the drives support Firewire 400 connection too, I connected the first to the Firewire port. I used the latest GParted livecd, to change the partition labels, because they were both the same (from factory). I was able to see both mounted and working (however, I'm not sure that the powerdown function works properly; I need to check it).

I have in mind to try a system repair from the installation cd. I hope that there is no problem with the motherboard (I never was very satisfied from it).

Thank you for the help. I'll post further news here, of course.

I've seen this more often. It appears the problem (most of the time) has to do with unclean unmounting... something XP is very vulnerable for. I must add though that my experience is with USB sticks, that are FAT formatted.

I don't know how Windows handles NTFS formatted external drives, but you could check under Linux to see if there's a /system directory in the root, and some driver files, also in the root. Under Windows these are hidden, but under Linux they show up. You could try deleting them.
I've seen two types of responses from a Windows system after this procedure... 1) all is well again (driver gets reinstalled) or 2) XP crashes (although SP3 seemed to fix this).

Another thing you could try is hook the external disk to another Wintel. This may cause some unknown magical process to fix everything and the drive is fine again. Or not.

In all cases: YMMV