vm with fc 14 won't boot after last kernel update

[Barry]

I had an instance of FC 14 running in a kvm vm on a centos 5.6 box.
After updating the kernel today, that vm refused to boot. I'm bumped
into a grub menu. Grub doesn't seem to be able to find the boot image or
the root partition. There are two othere vm instances (FC 13, and Winxp)
that are fine.

Has anyone else seen this? I don't know my way around grub well enough
to get it going. As an expedient I simply created a new instance, but
I'd like to know what went wrong.

Thanks in advance.