I can boot after upgrade from fc4 to fc5
 

because I have some software installed in fc4, and I choosed upgrade instead of
reinstalling. I download iso and burn dvd.

after upgrade, I can not boot the new sys. it stopped at this stage

#####################

Grub loading stage 2 ....

#####################

no other error message.

I have windows xp and fc4 originally, xp is installed on /dev/hda and fc4 in /dev/hdb.
Somebody told me possible reason is lda system??? but I did not found any screen
showing me to choose partition during the upgrade process. Another problem I got
is that I did not found windows boot option in grub.conf.

anybody can help me?

thanks.

When you did the upgrade, you should have let the installer update your GRUB boot information. From your description, I suspect that you chose some other option.

On the other hand, if that's the problem, you should have gotten a "File not found" message.

In any case, boot from the DVD using "linux rescue" at the prompt (or from the rescue disk -- CD 5, I believe) do a chroot /mnt/sysimage to your upgraded installation, and try a grub-install to reinstall GRUB.

Of course, if the rescue fails to find your new installation, you'll need to try other things.

CAUTION: Create an XP boot floppy first so you can boot to your XP system if something goes wrong.

u are right, I just reinstalled grub and it works now!