I have a dual boot setup with xp on one hd and ubuntu on a second hd. I recently upgraded to 10.04 and started getting the message on my monitor saying "input signal out of range". I searched on how to fix this and was advised to do this: " sudo dpkg-reconfigure xserver -xorg " and this unfortunately screwed up my boot options and would no longer go into ubuntu. So me thinking I was being clever, decided to format the partition with ubuntu on and now my PC just tries to boot into XP but loops before the XP splash screen. I don't want to have to flatten my PC as there is too much stuff on it that hasn't been backed up recently, and I'm sure its just a matter of tweaking bootloader or mbr or grub or something. Can anyone help me please???

This doesn't happen, can you define that better?

Boot from your Windows XP CD and head to the recovery console run "fixmbr" and "fixboot". Or try safe mode.

One you have XP working again you can try reinstalling Ubuntu.

Also, worst comes to worst, you could boot from a recent Linux live CD and access your hard drive and move files off.

If you have a Xp install disc can run the fixmbr command from recovery mode or reinstall linux to reinstall grub.

Before re-installing Ubuntu, you could try choosing the update option. The trick works in Fedora: the installer find nothing to update but the damaged bootloader.

Thanks folks - I ran the XP recovery and did fixmbr and this worked. Anyone know why the sudo command I used affected the ubuntu boot? I used to have it automatically going into xp after 15 secs (blame the wife) but it wasn't doing this it flashed up then gave me a command line which I then had to esc to get to the os choice screen.

I'll reinstall ubuntu anyway and try again.....

"dpkg-reconfigure xserver-xorg" would not affect grub in any way shape or form. You did something else or are not explaining clearly enough.

This smacks of KMS.
Bootloaders are generally blamed for a lot of things. Try booting from "recovery mode" - in almost all cases you'll get through the boot and find your error elsewhere. Lame bootsplashes just hide everything.

A re-install will probably work fine - Ubuntus "upgrades" can be a real can of worms; to be avoided at all costs.

Whats KMS??

kernel mode setting.