Frozen Mac

I HAVE to boot OS X into "safe mode" by holding down the SHIFT key or else the computer will not start…. It just comes up with the apple, then the blue gray screen and then the rainbow pinwheel.
I have tried the command-option-P-R and still end up having to turn the computer off and start in safe mode
I’ve tried to create another profile and boot into that one, Doesn’t work either
I’ve done the software updates to try to fix my problem so I can boot normally, and tested everything with tech tool deluxe and everything passed!
What the heck is the problem??? I can not figure it out and I don’t have the disc for os x 10.5.7 because I lost it…..
ALSO, since I’m booting in safe mode, my speakers don’t work (as expected) so I can’t continue this way…. PLEASE HELP!!!

Do you have a backup drive that you can try to boot from?

no... just the one drive

P.S.
I used to have a PC and it kept crashing (of course) so that's why I got a MAC.... GRRR... also not very familiar with them, just doing my research and experimenting with fixes....

Think you are going to need the Leopard disc alas as that is the best trouble shooting utility available. When you get the Leopard disc, burn a copy and use that for emergency running repairs.

Another option is to try and boot from the original system discs which came with your iMac. POop in the disc, reboot, hold down D and see if you get the option of using Apple Hardware Test.

Thanks... I will try to get a copy. I do have DiskWarrior and ran that from the utilities safe mode and it said everything was fine...AHHHH! Nothing is working. I think you're right though, I'll have to reinstall it and or repair from the disc