iBook g4 help - grey screen of death?

Ok, so here's the deal.

First off I would like to say that I have searched for a while everywhere and didn't find anything.

I have an iBook g4 that I got from my parents. I had to replace the hard drive because that failed and ever since then it has been acting a little strange (I had to squeeze the hard drive to start it, hard drive randomly disconnects when in use, etc). Anyway this started a week ago and the only thing it does when it boots up is it does the apple chime then stays at a grey screen for about 3-5 minutes then goes to the screen where it shows the flashing finder question mark folder thing then it will shut down after 10 mins or so.

It has had panther, tiger, and leopard all installed on it and they all worked fine but leopard was a bit shaky so I reinstalled tiger.

It will boot fine off of the install dvd and will run an ubuntu live cd perfectly but I think the reason that it will not boot is that I was repartitioning the disk when the computer lost power and since then it will not work correctly. None of the install disks say there is a hard drive but the drive spins up, I think it might be the connector as well but I don't know.

Any help would be appreciated on solving my problem.

Thanks in advance if you decide to help.

Ok, thanks Strimkind ill try that and ill get back if it helps or not. I really appreciate the help because I use this computer for school and whatnot. So Thanks.