strange cursor clicks

I don't know if this happens to other people, but whenever i'm typing an email in Entourage or using Word, wherever the mouse cursor is, it would automatically click and make the typing cursor to wherever the arrow was and make me lose my position in my typing. Whenever that happens, i heard this sound from my computer like the sound that you'd hear when you're saving a document. This happens like, every minute or so. Is there a way to disable that?? It's getting really annoying, i can't finish my emails, i can't type without the cursor going off to another place....

 

it happens with everything. Even as i type this message. I have a powerbook g4, i bought it just over a month ago. it's not a mouse problem. it's a cursor problem... (i don't quite know how to explain it). It's the cursor arrow that's causing problems, so if i'm typing something, wherever the arrow may be (most of the time i have the arrow somewhere else in the screen that i'm typing), after a minute or so, i'd see my typing cursor move to wherever the arrow is. And this causes whatever that i'm typing to shift to another part of my text.

 

ok thanks.

let me pay attention to my typing and see if that's the case.