环境:win7 + ubuntu12.04

原因：ubuntu引导不识别win7系统，胡乱执行grub修复，导致双系统均无法启动。

出现异常信息：no boot signature in partition。

解决：

1.   通过USB系统镜像启动ubuntu。制作镜像。

2.   设置你的bios为USB启动，进入ubuntu。

3.   在线安装lilo。

ubuntu@ubuntu:~$ sudo apt-get install lilo
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following extra packages will be installed:
  mbr
Suggested packages:
  lilo-doc
The following NEW packages will be installed:
  lilo mbr
0 upgraded, 2 newly installed, 0 to remove and 408 not upgraded.
Need to get 413kB of archives.
After this operation, 1,315kB of additional disk space will be used.
Do you want to continue [Y/n]? y
Get:1 http://mirror.bjtu.edu.cn/ubuntu/ lucid/main mbr 1.1.10-2 [23.0kB]
Get:2 http://mirror.bjtu.edu.cn/ubuntu/ lucid/main lilo 1:22.8-8ubuntu1 [390kB]
Fetched 413kB in 3s (124kB/s)
Preconfiguring packages ...
Selecting previously deselected package mbr.
(Reading database ... 129801 files and directories currently installed.)
Unpacking mbr (from .../archives/mbr_1.1.10-2_i386.deb) ...
Selecting previously deselected package lilo.
Unpacking lilo (from .../lilo_1%3a22.8-8ubuntu1_i386.deb) ...
Processing triggers for man-db ...
Setting up mbr (1.1.10-2) ...
Setting up lilo (1:22.8-8ubuntu1) ...

WARNING: kernel & initrd not found in the root directory (/vmlinuz & /initrd.img)
WARNING: Do NOT reboot or LILO may fail to boot if your kernel+initrd is large.
WARNING: Please read /usr/share/doc/lilo/README.Debian
ubuntu@ubuntu:~$

安装过程中，会得到如下lilo的配置提示，按OK就行了：

Package configuration

┌───────────────────────────┤ Configuring lilo ├────────────────────────────┐
 │                                                                           │ 
 │ LILO configuration                                                        │ 
 │                                                                           │ 
 │ It seems to be your first LILO installation. It is absolutely necessary   │ 
 │ to run liloconfig(8) when you complete this process and execute           │ 
 │ /sbin/lilo after this.                                                    │ 
 │                                                                           │ 
 │ LILO won't work if you don't do this.                                     │ 
 │                                                                           │ 
 │                                  <Ok>                                     │ 
 │                                                                           │ 
 └───────────────────────────────────────────────────────────────────────────┘

ubuntu@ubuntu:~$ sudo lilo -M /dev/sda mbr
Backup copy of /dev/sda in /boot/boot.0800
The Master Boot Record of  /dev/sda  has been updated.

ubuntu@ubuntu:~$ sudo -s -H

root@ubuntu:~# cd /boot/

root@ubuntu:/boot/# sudo mount /dev/sda7 /mnt

##/dev/sda7为ubuntu系统所在分区

root@ubuntu:/boot/# sudo grub-install --boot-directory=/mnt /dev/sda

root@ubuntu:/boot/# reboot

重启之后发现ubuntu进入grub>引导了。

4.  设置grub。

grub>set root=(hd0,7)

grub>set prefix=(hd0,7)/boot/grub

## 此目录主体tab键提示查找

grub>insmod (hd0,8)/boot/grub/normal.mod

grub>normal

## 执行完毕直接从硬盘进入ubuntu系统

## 进入ubuntu后执行update-grub ，所有工作完成

## 重启ubuntu系统后，发现还是要一直设置grub引导。

## 执行boot-repair，这下好了

root@ubuntu:/boot/# update-grub

root@ubuntu:/boot/#sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update

root@ubuntu:/boot/#sudo apt-get install -y boot-repair && boot-repair

## 此处boot-repair有可能安装不成功，重新修改镜像源就可

##Ubuntu Software Center 中修改即可

等待一会，就会出现Boot Repair的软件界面了，点击上面的“recommended repair”按钮，等待一会儿，就会跳出修复成功。

至此ubuntu可以正常引导了。

5.   修复win7引导

通过系统光盘使用winpe进入系统，使用u盘里下载好的BCDautofix软件，执行以下。

回到ubuntu在执行一下

root@ubuntu:/boot/# update-grub

至此win7 + ubuntu都能够正常的使用，正常的引导了。

参考链接：

##修复boot引导

http://www.cnblogs.com/khler/archive/2011/01/31/1948485.html

## grub引导设置

http://www.laifuying.com/archives/436

##u盘引导制作

http://os.51cto.com/art/200911/163420_all.htm