我最近安装了 Xubuntu 12.04。安装后我立即更新了所有软件包，但有一个软件包grub-pc安装失败。我不确定是什么原因导致失败，但错误如下：
bui@bluefly:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages have been kept back:
hplip hplip-data libhpmud0 libsane-hpaio linux-generic linux-headers-generic linux-image-generic printer-driver-hpcups printer-driver-hpijs
0 upgraded, 0 newly installed, 0 to remove and 9 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue [Y/n]?
Setting up grub-pc (1.99-21ubuntu3.1) ...
cp: reading `/usr/share/grub/unicode.pf2': Input/output error
cp: failed to extend `/boot/grub/unicode.pf2': Input/output error
dpkg: error processing grub-pc (--configure):
subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
grub-pc
E: Sub-process /usr/bin/dpkg returned an error code (1)
bui@bluefly:~$
我很担心，以为如果重新启动，我的 GRUB 会无法运行。不幸的是，它确实无法运行，现在我遇到了这个错误：
error: ELF sectors outside core
grub rescue>
我被困在这里，不知道该采取什么措施。如果能得到建议，我将不胜感激。如果有帮助的话，这是我在重启之前记录的启动信息脚本日志：
/dev/sda 是我的硬盘，/dev/sda1 是 Xubuntu 所在的分区。谢谢。
编辑：我运行了boot-repair，但是失败了，仍然出现相同的 GRUB 错误。这是输出日志：http://paste.ubuntu.com/1119223/