Is my hard drive thrashed?

[Dan Hensley]

I'm using FC6.  This morning when I turned on my computer, it booted up 
fine.  I logged in fine.  As soon as I logged in, I started Firefox.  It 
seemed to take a long time and never came up.  So I tried launching 
something else from the Gnome taskbar.  It was unresponsive.  I hit 
CTRL-ALT-BKSP to log out of X.  It went to a text screen and I saw lots 
of messages about ata1 errors and non-responding ports and stuff like 
that.  After a long while things didn't change, so I turned off the 
machine and tried booting again.  The BIOS couldn't find my hard drive 
(the only SATA drive on the system).  I replaced the drive cable, and 
after that the BIOS found the hard drive.

When I try booting, I see the following grub message:

GRUB

At this point the computer hangs.

So I booted up the rescue CD.  I chrooted to my filesystem and ran 
grub-install /dev/sda.  I had to do this about a month ago (I have no 
idea why), and that fixed the problem.  But this time it did not fix the 
problem.

My question is, how can I get out of this bind?  Is my hard drive 
trashed, or just the boot record?  Or is it something else?  When I boot 
off the rescue CD the hard drive contents appear fine.  I just can't get 
it to boot off my system.

Nothing changed between yesterday except for yum-updating about 78 files 
including firefox.

Thanks for any help,
Dan