F7-x86-64 Stopped Booting - GRUB Issue

[Raymond C. Rodgers]

Up until this past weekend, I had a very happy dual boot configuration 
with Windows XP (32 bit) and Fedora 7 x86-64 on my machine. It had been 
a few weeks since I had last booted Linux, and I hadn't had any problems 
with it before now. I got the latest kernel and other updates via yum as 
I normally do, but when I went to reboot, all I got was a simple text 
message saying "GRUB" in the upper left hand corner of my screen, and 
that's all I've gotten ever since.

I just tried to do an upgrade install of Fedora 7 to fix the issue, and 
specifically told it to replace the boot loader configuration on the 
proper partition, but that didn't work to correct the issue. A little 
more detail is that I'm using the Windows XP boot.ini/boot configuration 
to load WinXP or to load GRUB which in turn loads Linux. Could this be 
an issue where I need to get a new copy of the boot sector for F7? 
(Booting the rescue CD, and getting the first 512 bytes of the boot 
partition, and copying it over to the Windows partition so it can 
properly init everything?) If not, what should I do to recover this 
installation?

Thanks,
Raymond

P.S. For the record, SELinux is disabled if that helps any.