Will My Hard Drive Be Deleted???, Please help Options

[angryman]

Ok, can any one tell me what will happen if I insert the install CD for my PowerBook, hold down C and restart my computer?

Will my hardrive be wiped?

Here is some background:

I have a gig on thursday night (at the Trafalgar Hilton if you fancy it: its £20 per drink by the way!)

But my PowerBook is screwed. When ever I open any Audio Applications after 20 minutes I get a loud fuzzing noise (quite like the noise you get when you use demo soft synths and the like) but the noise is relentless and only stops if you close the audio apps and restart them. Obviously I cant do this twice in my set as that would really suck.

I have tried repairing permissions (thanks Lepetitmartien) but unfortunately this didn't work. Apple told me to do the install, hold down C thing but I am worried that my whole harddrive will get deleted!

Can anyone help???