Partition troubles! Help!

Hi all,

I've got a serious problem here. I've just tried to update my PC's 500 GB drive to a 1TB drive. The data I was going to copy with Acronis True Image 10 (which I've used in the past an never gave me any grief up to now).

I selected the source and target disks correctly. The I gave the go to the system, and the process started. Only, usually the system locks the partitions or something, then reboots the system to do the necessary disk cloning in some sort of DOS modus, and then returns to windows.
Now the system took ages to lock the system partitions. I got suspicious and cancelled the process.

Now I can't access the source drive any more!! AAaargh! I can still see both partitions on the disk via XP's disk management tool, but I see the drives have no drive letter and also don't show up in windows explorer. I'm pretty sure the data is still all there, after all, this was the source drive.
How can I 'unlock' these partitions again?

Thanks VERY much for any input you can provide!

My guess would be that it changed the partition type. Get a Linux Live CD and run fdisk against the drive. It should allow you to assign the correct partition type to all of the partitions.

My assumption could be totally wrong, though.

I'll try that, thanks!

Ok, now typing this from within Knoppix.

QTParted clearly shows all partitions, without a problem. Konqueror is even able to access them! I can see all the files from within Linux and I haven't even changed anything!

I'll try rebooting into windows now. Maybe it's already fixed, who knows?

Ok, now back in XP. Didn't work. (not really surprised since I didn't change anything)

I Ok, this does mean I can access the data. Worst case, I simply copy the files via Knoppix (how that Linux NTFS writer doing these days?)

I'll search a bit further first though. By now I have been assured my data is still there. I just need to change something to the partitions. (don't know what exactly, and with which program)

Replying to myself:
I can see in the Windows Disk Management utility that both partitions are still there on the disk, but no drive letter seems to get assigned to the partitions! Very strange.
I guess I can simply add a drive letter, but is it dangerous to do this? (isn't this 'forcing' things?) I really don't want to risk losing my data!

Any Linux partition editor should show you the "partition type" or "partition ID". NTFS partitions should be 0x86 or 0x87 and FAT32 should be 0x0b, IIRC. My guess is that those partitions' IDs have been changed to something that Windows doesn't recognize. Change them back.

Ok, update. I managed to fix this issue by simply re-assigning a drive letter in windows to the partition. (forcing it, if you will). But it works, no problem.

I've just stumbled onto a different problem, but I'll create a new post for that since it has nothing to do with this problem.