I am attempting to boot up my 2009 MacBook Pro, but when it starts it immediately shows a white screen with a 'question mark folder' — it keeps blinking until the computer shuts down (unless I keep it in the charger, then it just goes on).
I have tried to do the start up whilst holding down the option/alt button, and only the arrow comes up. I don't have the startup system disk (or any other) but the system has been updated to OS X Mountain Lion from the Mac App Store.
Before this, there had been other problems: when I deleted things they didn't go in the Trash but instead it looked like it just deleted it completely. After some time it wouldn't save or download, saying there wasn't enough space (even though I deleted items).