Can't boot Win XP after installing Ubuntu 10.10 side by side

Forgot to add: I installed Ubuntu on Windows XP machine by using Ubuntu installation to partition the disk.

output of sudo fdisk -l

 Device Boot Start End Blocks Id System
/dev/sda1 1 914 7341484+ 12 Compaq diagnostics
Partition 1 does not end on cylinder boundary.
/dev/sda2 * 914 20345 156072774+ 7 HPFS/NTFS
/dev/sda3 20345 38914 149155841 5 Extended
/dev/sda5 20345 38155 143057920 83 Linux
/dev/sda6 38155 38914 6096896 82 Linux swap / Solaris

Try:

sudo apt-get -y install os-prober; clear; sudo os-prober; sudo update-grub

HTH

This is what I see after trying out the suggestion of actionparsnip (thanks for taking the time) but it still gives me the blank screen with blinking line - after trying the above, powering down and rebooting:
/dev/sda1:Windows NT/2000/XP:Windows:chain
/dev/sda2:Microsoft Windows XP Professional:Windows1:chain
Generating grub.cfg ...
Found linux image: /boot/vmlinuz-2.6.35-28-generic-pae
Found initrd image: /boot/initrd.img-2.6.35-28-generic-pae
Found memtest86+ image: /boot/memtest86+.bin
Found Windows NT/2000/XP on /dev/sda1
Found Microsoft Windows XP Professional on /dev/sda2
done

Do you see any GRUB selections when booting -- like the kernel versions of Ubuntu and then Windows XP? Or does your computer immediately boot to Ubuntu? If this is so, you might want to try press and holding SHIFT upon booting to load GRUB. From there you can select the OS you want.

If not, tell us what you see.

Thanks, JeanAustinR.

On reboot, there was a choice - Ubuntu being the first and timed to something like 7 seconds; then a four or five lines, the last line being Windows XP. However, choosing it did not help (the one immediately above was WIndows 2000/NT something and choosing that at the next boot also didn't help.

After looking at various posts on this subject, I was not sure if there was a common solution. In the end, I thought there might have been some incompatibility/issue with XP that was updated fully just before Ubuntu 10.10 installation. I re-set the computer to factory settings and installed Ubuntu alongside after partitioning with Ubuntu's installation process. Then Windows booted fine. Then of course I updated Windows

I know this is not at all a perfect solution. In my case, I did not have too many programs installed in Windows before doing Ubuntu installation.

Best of luck to those suffering this issue.

blank screen with blinking line: http://www.ubuntugeek.com/how-to-fix-ubuntu-10-04-lts-lucid-blank-screen-at-startup.html