hi guys, sry if im posting this in the wrong place but im in a kind of a hurry. i was upgrading from 10.5 to 10.6 using the dmg of the installer dvd. the installer was working fine but it quitted and tended to restart after like 15 minutes. i thought this was normal but during the booting i get a gray screen with the icon of a folder with a questionmark on it and it just keeps on flashing. i rebooted the system and held down the option key so i got to choose between my os' drive and a windows drive (which is kind of weird cause i dont have a windows installation on my mac i only have ubuntu 9.04). i choose the os' drive and i can boot into my previous os, 10.5.8. i have no idea why this has happened and how i can fix it? would you guys be kind enough to help me out? i really need my laptop for this weekend.