It looks like GRUB managed to get some files onto sda1; this is probably the cause of your troubles. I recommend you use a LiveCD and delete this from sda1:
/boot/grub/core.img Windows does not like seeing 2 sets of files that begin with boot.
Then, reinstall GRUB:
https://help.ubuntu.com/community/Grub2#Reinstalling%20from%20LiveCD
Make sure you mount sda5 (the Ubuntu partition) and install GRUB to the MBR of sda.
Boot Info Script 0.55 dated February 15th, 2010
============================= Boot Info Summary: ==============================
=> Grub 2 is installed in the MBR of /dev/sda and looks on the same drive in
partition #5 for (,msdos5)/boot/grub.
sda1: __________________________________________________ _______________________
File system: ntfs
Boot sector type: Windows Vista/7
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files/dirs: /bootmgr /Boot/BCD /boot/grub/core.img
sda2: __________________________________________________ _______________________
File system: ntfs
Boot sector type: Windows Vista/7
Boot sector info: No errors found in the Boot Parameter Block.
Operating System: Windows 7
Boot files/dirs: /Windows/System32/winload.exe
sda3: __________________________________________________ _______________________
File system: Extended Partition
Boot sector type: -
Boot sector info:
sda5: __________________________________________________ _______________________
File system: ext4
Boot sector type: -
Boot sector info:
Operating System: Ubuntu 10.10
Boot files/dirs: /boot/grub/grub.cfg /etc/fstab /boot/grub/core.img
sda6: __________________________________________________ _______________________
File system: swap
Boot sector type: -
Boot sector info:
=========================== Drive/Partition Info: =============================
Drive: sda ___________________ __________________________________________________ ___
Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
Partition Boot Start End Size Id System
/dev/sda1 * 2,048 206,847 204,800 7 HPFS/NTFS
/dev/sda2 206,848 180,728,498 180,521,651 7 HPFS/NTFS
/dev/sda3 180,729,854 312,580,095 131,850,242 5 Extended
/dev/sda5 180,729,856 307,111,935 126,382,080 83 Linux
/dev/sda6 307,113,984 312,580,095 5,466,112 82 Linux swap / Solaris
blkid -c /dev/null: __________________________________________________ __________
Device UUID TYPE LABEL
/dev/sda1 78AE271DAE26D402 ntfs System Reserved
/dev/sda2 78502F7F502F42EC ntfs
/dev/sda3: PTTYPE="dos"
/dev/sda5 12fdf0b1-fdb4-418f-8e26-1369be50413f ext4
/dev/sda6 d01c0778-8a17-4cda-b716-41dd16980609 swap
/dev/sda: PTTYPE="dos"
error: /dev/sdb: No medium found
============================ "mount | grep ^/dev output: ===========================
Device Mount_Point Type Options
/dev/sda5 / ext4 (rw,errors=remount-ro,commit=600)
=================== sda1: Location of files loaded by Grub: ===================
??GB: boot/grub/core.img
=========================== sda5/boot/grub/grub.cfg: ===========================
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#
### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
set default="0"
if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi
function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}
function recordfail {
set recordfail=1
if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}
function load_video {
insmod vbe
insmod vga
}
insmod part_msdos
insmod ext2
set root='(hd0,msdos5)'
search --no-floppy --fs-uuid --set 12fdf0b1-fdb4-418f-8e26-1369be50413f
if loadfont /usr/share/grub/unicode.pf2 ; then
set gfxmode=640x480
load_video
insmod gfxterm
fi
terminal_output gfxterm
insmod part_msdos
insmod ext2
set root='(hd0,msdos5)'
search --no-floppy --fs-uuid --set 12fdf0b1-fdb4-418f-8e26-1369be50413f
set locale_dir=($root)/boot/grub/locale
set lang=en
insmod gettext
if [ "${recordfail}" = 1 ]; then
set timeout=-1
else
set timeout=10
fi
### END /etc/grub.d/00_header ###
### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
### END /etc/grub.d/05_debian_theme ###
### BEGIN /etc/grub.d/10_linux ###
menuentry 'Ubuntu, with Linux 2.6.35-22-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod part_msdos
insmod ext2
set root='(hd0,msdos5)'
search --no-floppy --fs-uuid --set 12fdf0b1-fdb4-418f-8e26-1369be50413f
linux /boot/vmlinuz-2.6.35-22-generic root=UUID=12fdf0b1-fdb4-418f-8e26-1369be50413f ro quiet splash
initrd /boot/initrd.img-2.6.35-22-generic
}
menuentry 'Ubuntu, with Linux 2.6.35-22-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod part_msdos
insmod ext2
set root='(hd0,msdos5)'
search --no-floppy --fs-uuid --set 12fdf0b1-fdb4-418f-8e26-1369be50413f
echo 'Loading Linux 2.6.35-22-generic ...'
linux /boot/vmlinuz-2.6.35-22-generic root=UUID=12fdf0b1-fdb4-418f-8e26-1369be50413f ro single
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-2.6.35-22-generic
}
### END /etc/grub.d/10_linux ###
### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###
### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry "Memory test (memtest86+)" {
insmod part_msdos
insmod ext2
set root='(hd0,msdos5)'
search --no-floppy --fs-uuid --set 12fdf0b1-fdb4-418f-8e26-1369be50413f
linux16 /boot/memtest86+.bin
}
menuentry "Memory test (memtest86+, serial console 115200)" {
insmod part_msdos
insmod ext2
set root='(hd0,msdos5)'
search --no-floppy --fs-uuid --set 12fdf0b1-fdb4-418f-8e26-1369be50413f
linux16 /boot/memtest86+.bin console=ttyS0,115200n8
}
### END /etc/grub.d/20_memtest86+ ###
### BEGIN /etc/grub.d/30_os-prober ###
if [ "x${timeout}" != "x-1" ]; then
if keystatus; then
if keystatus --shift; then
set timeout=-1
else
set timeout=0
fi
else
if sleep --interruptible 3 ; then
set timeout=0
fi
fi
fi
### END /etc/grub.d/30_os-prober ###
### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###
### BEGIN /etc/grub.d/41_custom ###
if [ -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###
=============================== sda5/etc/fstab: ===============================
# /etc/fstab: static file system information.
#
# Use 'blkid -o value -s UUID' to print the universally unique identifier
# for a device; this may be used with UUID= as a more robust way to name
# devices that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point> <type> <options> <dump> <pass>
proc /proc proc nodev,noexec,nosuid 0 0
# / was on /dev/sda5 during installation
UUID=12fdf0b1-fdb4-418f-8e26-1369be50413f / ext4 errors=remount-ro 0 1
# swap was on /dev/sda6 during installation
UUID=d01c0778-8a17-4cda-b716-41dd16980609 none swap sw 0 0
=================== sda5: Location of files loaded by Grub: ===================
137.7GB: boot/grub/core.img
127.2GB: boot/grub/grub.cfg
93.4GB: boot/initrd.img-2.6.35-22-generic
137.7GB: boot/vmlinuz-2.6.35-22-generic
93.4GB: initrd.img
137.7GB: vmlinuz
=======Devices which don't seem to have a corresponding hard drive==============
sdb