Question : Problem: Dell laptop randomly freezes - cursor randomly jumps to another sentence

I have a dell inspirion 7500 laptop running WIN XP Pro.  I have taken it to a repair shop and they cleaned the dust bunnys out and replaced some bad memory HOWEVER it still randomly shuts down, just not when the repair shop had it.  Just before it seizes up it makes a sound as though it is try to access the CD Rom which I have recently replaced with a new DVD drive.

ALSO when typing along in any application the cursor will randomly move and I'll find myself in the middle of some other sentence. The laptop is 6 years old

Answer : Problem: Dell laptop randomly freezes - cursor randomly jumps to another sentence

try booting from a bootable cd like knoppix; if this runs fine, your hardware is ok; if not it is bad.
www.knoppix.org