flashing questionmark folder on g5

ok so the other day i was working on a paper and the imac froze, this is weird, i thought, this had never happened before. so i restart the computer and i get a folder with a mac face and a flashing question mark. what the ****? so i tried several times restarting it and it never worked, so i took it to the apple store. the guy there held down x and it eventually sarted up osx, he even opened itunes and showed me my songs, so i guess the harddrive isnt ruined. when i got back the computer started up fine, after about fifteen minutes it had gone to sleep and when i woke it up it froze, i could move the mouse but the dock wasnt responding and i couldnt open anything. so thats my story, about once out of 7 times osx will open, but it freezes almost immediately. when i inserted the osx install cd, i go through the steps and when it gets to the "select a volume destination" there is no harddrive to select. i really need help this is sooooo frustrating! thank you guys for bearing with me.

tomasismyname said:

....when i inserted the osx install cd, i go through the steps and when it gets to the "select a volume destination" there is no harddrive to select. i really need help this is sooooo frustrating! thank you guys for bearing with me.

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That is a sign that there is seriously something wrong with your HD. Take it back to the store to have a tech look at it and schedule a warranty repair.