Problem when starting up showing boot screen

k.panic has the answer.

That’s weird. Even if you don’t have a startup volume specified, it shouldn’t bring you into that menu.

Try resetting your PRAM according to this kbase article: http://support.apple.com/kb/ht1379

Like the above poster said, go into System Preferences, go to Startup Disk and select Macintosh HD (or whatever you’ve named your hard drive).

via Apple – Support – Discussions – problem when starting up ….