dual boot - xp behaves strange

[Rares Vernica]

Hi,

I set up a dual boot environment with Ubuntu and XP. Grub is installed 
on Ubuntu partition and the intention is to have the Ubuntu partition 
bootable. The XP partition just needs to be visible.

It seems to work. I can boot in Ubuntu just fine. The problem is when I 
boot in XP, it changes the partitions. XP seems to hide the Ubuntu 
partition and make the XP partition bootable.

I wonder why this happens. I had this setting before and it worked just 
fine.

One more think, I first installed Ubuntu and then Windows.

Thanks a lot,
Ray