I have a dual-boot system which had a windows XP (amd64) NTFS partition as the first partition, and several regular (not lvm) ext3 partitions containing Fedora 9 (amd64).
GRUB was installed in the mbr and was the main boot loader.
I used fuse-ntfs driver on the linux side and ext2-IFS on the windows side. Both partitions were mounted with write access and everything seems to work well until now.

I just rebooted my system only to find out a black screen, containing only the string "GRUB" and the computer beeps unstoppably.
I tried to boot the fedora rescue mode and reinstall grub, no luck.
I booted the computer from windows xp installation disk and went to the recovery console only to find out that it cannot read my NTFS partition at all. Running chkdsk said that the partition contains some unrecoverable errors.

I ran fixmbr as my last hope, rebooted, and surprisingly GRUB showed up. The fedora installation booted fine, and all ext3 partition seems to be intact.
The NTFS partition, although, seems to be dead. ntfsfix cannot correct it and I cannot read it from linux.
Luckily, there was nothing critically important to my on that partition, but I would really like to know how to fix the partition without reinstalling windows XP.

Now, there are several things which I could not understand:
1. How did the NTFS partition got corrupted in the first place.
2. How does that corruption affected GRUB (It sits on the MBR)
3. Why did grub-install command didn't fix grub
4. How come that window fixmbr command, which is supposed to restore NTLDR, fixed grub.
5. How can I restore the NTFS partition?

Sometimes the answer is simply: "Gremlins"

Since you have Fedora working, open a terminal, "su" to root, and run "fdisk -l". (Actually, on Fedora, you may need "su -" or "/sbin/fdisk -l")
Post the results here.

Also, assuming that fdisk tell us the NTFS partition is there, you can mount it and look for the standard Windows files.

Too right....

I find it interesting that your NTFS partition and your MBR appeared to both get hosed, at least somewhat, during this process. Is your NTFS partition by any chance the first one on the disk?

Yes, it is.
The partition itself seems to be alright, and also recognized as an NTFS filesystem on GParted. The problem is the filesystem corruption. I tried chkdsk, ntfsfix, testdisk and a regular mount. None of them seems to extract any file data.
Is the ntfs-3g driver really stable as documented?

If an NTFS partition needs fixing, it *has* to be fixed from Windoze. That's the situation you put yourself in when you choose to use a proprietary format. No open source tool I know of will do the job, although the ntfsprogs project has future plans.
I only ever share (as rw) data partitions that I can afford to lose - certainly not the 'doze system/boot partitions. There are also those mundane concepts such as backups - 3g is good, but all code fails sometime. Can be as simple as a power glitch for a journalled filesystem like NTFS.

How many hard disks are on the system ???. You were asked to provide an "fdisk -l" output; while you're at it, post the output from this for each disk - it merely dumps out the first sector (MBR plus partition table) in ASCII

So that means that if windows itself fails to fix the filesystem, it's lost?

This is the only disk in the system.