Hi I have fedora 12 installed.. it was going very well with windows xp. I choose ext4 partition for it.

I installed it from the liveCD, i then made the usb version of it. I tested the usbversion, i was able to access the hard disk and auto mount all the partions, even linux partion.

Suddenly i restarted my computer today and found out that the grub is coming up fine but when i choose to boot, it fails saying

Windows XP is coming up fine, no problems in that.

OK..so i plug in my usb device and boot from usb to the live fedora version, it boots up fine, but now its not able to recognize my hardisk..

While checking the various mounts.... using the "disk utility"..it says unrecognized hard-disk...

If i start the installer again, it says
This is really strange.. it was working fine yesterday and now nothing seems to be working, except the windows xp

i later checked the disk using windows and it has no problem in recognizing the various disk partitions using control panel >> administrative tool >> computer management

Now i have only windows xp with me, i updated my fedora also installed VLC and Wine.. now its gone.. any ideas suggestion what could have gone wrong.. or like what possible way i can get it back..

The MBR seems to be fine as i see the GRUB loading, its that when i select the fedora menu, it starts of with the starting screen

As i have Nvidia drivers installed... i see the 3 colored line moving at the bottom of the screen.. but ends up with an error

Could be the disk drive bus being renumbered when the USB is plugged in. Have you tried disabling it in bios ?

Well its somehow solved.. I tried other linux distros but none of them would recognize my hardisk, it was getting the name it should /dev/sda1 but it said unrecognized filesystem.

So here is what i did, i got my external hardisk plugged in and installed SuseLinux on that, and while installing the grub boot manager it somehow discovered all the partitions. I did not have to try out adam's option but that could also be tried.

Later i logged in to the fedora partion and reinstalled grub, its all back to normal, no idea what happened but this sure helped to sort the issue.. strange!!! but working..