No, vista / xp partition did not make problem here ! I have a computer at hoem, where I installed XP; Windows 7; Fedora 14 and SLES 11 (for R & D purpose) on a same HDD capacity 320 GB and they all r work fine. when I first installed, I got the same problem as u mentioned here ! the main cause is ChainLoader error. U have to install them sequentially like 1st install XP; then Vista and lastly Ubuntu (if it is server, then very good). After that Ubuntu may the default boot and the two r as “Other” or “Windows” label. Now check the file called “/boot/grub/menu.lst” and observe the line like that….
Remember, the digits may change according to ur scenario. If u have only one hdd then the 1st line is same. If there is nothing like in menu.lst then u have to add these lines manually.