If you have either a Win XP or a FC3 rescue CD, you are in no trouble at all
Just put in the FC3 CD (presuming you have one) and follow the instructions. This will get you into single mode (text console).
Once there type :
grub or /sbin/grub and this will get you into your grb console (example: grub>)
Once in there, type:
--> where hd0 is your primary harddisk, presuming you have your boot partition on your primary harddisk, if you have a boot partition, else use the / partition. The 1 is used to identify your boot partition if you have one, else use the / partition. Keep in mind that partitions start with 0, so presuming Win XP is on hd0,0 = C
One more thing. As other shells, this one supports auto completion using the TAB key, so use it, to see what options the commands use, and also to see what partitions and harddisks you have.
you can see your partition table using fdisk -l
try to identify your boot partition if you have one, else use the / partition.
The output of root (hd0,1) will be a description of the filesystem it has selected.
setup(hd0), presuming this is where you want to install grub. This will install it to the MBR, thus giving you the GRUB boot loader.
This will output some lines, which you check for errors. there shouldn't be any.
Now you're done. Type quit, to get out of grub shell, and reboot, using the command reboot.
Now you should see the GRUB bootloader, from wheere you can select what OS you want to start.
Ok presuming you don't have a FC3 rescue disk. No problem, as long as you have your XP CD. Put it in and start the recovery console of it. Once there, you will be prompted for the administrators password. You will be dropped into console mode, similar to linux, just a C:>
Here execute the command fixmbr, which will wipe out GRUB from the MBR, thus giving you free way to your Win XP, without showing you that Linux is still on your computer. Once in Win XP, download the FC3 rescue CD and burn it, and then follow the upper instructions.
Just a description of the error you are having:
Grub is installed on your computer, as you can see Grub Loading stage 2....
However it seems it cannot find it's files. Maybe you changed something to alter the partition table, in which case, this usually happens. Think what did you do, to not do it again next time.