After Ubuntu is installed, XP or Win7 cannot be guided to solve the problem.

Since Ubuntu9.10 started to use grub2 to guide the system, the new grub2 boot configuration file is no longer a menu. lst, but/boot/grub. cfg file, which is different from the old version. For security reasons, this file is "read-only" by default, therefore, you must change the file attribute to "readable/writable" before modifying the file content. After sudochmod + w/boot/grub. cfg is added, the content is as follows: # DO

Since grub2 is used to boot the system in Ubuntu 9.10, the boot configuration file of grub2 is no longer menu. lst,
/Boot/grub. cfg file, which is different from the old version. For security reasons, this file is "read-only" by default, therefore, you must change the file attribute to "readable/writable" before modifying the file content.

Sudo chmod + w/boot/grub. cfg

The added content is as follows:
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by/usr/sbin/grub-mkconfig using templates
# From and settings from/etc/default/grub
#
### BEGIN/etc/grub. d/00_header ###
Set default = 0 // default start sequence
Set timeout = 5 // waiting duration
Set root = (hd0, 7) // directory where the boot file is located
Search -- fs-uuid -- set 98c1c189-b321-440d-89b5-7ff0723c83e2 // uuid of the root Partition

Set menu_color_normal = cyan/blue // set the background color
Set menu_color_highlight = white/blue // set the highlighted color.

# The text in the double quotation marks behind menuentry is the name of the startup project displayed on the Startup menu.
Menuentry "Ubuntu, 9.10 (linux 2.6.30-8-generic )"{
# Locate start Partition
Set root = (hd0, 7)
# Check UUID and start the system
Search -- fs-uuid -- set 98c1c189-b321-440d-89b5-7ff0723c83e2
Linux/boot/vmlinuz-2.6.30-8-generic root = UUID = 98c1c189-b321-440d-89b5-7ff0723c83e2 ro quiet splash
Initrd/boot/initrd. img-2.6.30-8-generic
}

# The Boot part of the XP system is the same as that of the old version.
Menuentry "Windows XP Pro "{
Set root = (hd0, 1)
Chainloader + 1
}

# Back up the file before changing it. The difference between UUID and disk is incorrect. My test has been successful. (Windows cannot be installed after Ubuntu is installed. No comparison guide interface. You cannot modify grub .)