I just got a 12 inch PB that has no OS disc, its got Leopard on, and I cant get it to boot at all. I get as far as the flashing question mark then thats it. I've tried: - holding various combination keys - burnt disc warrior on dvd - tried to boot to single user - holding the apple key and just getting and refrsh and arrow button Nothing seems to solve it :( Anything else I should try?

Looks like you've tried everything I'd try...Next I'd try zapping the PRAM http://support.apple.com/kb/HT1379 then I'd try to see if I can get my hands on an install DVD. Try Craigslist, ask to borrow the OS disc for a repair. Or buy a used Leopard disc online, with Snow Leopard coming out 3rd parties will probably try to clear out their inventory of Leopard discs. You really should keep an OS X install DVD because it's a life saver.