LAPTOP LOCKED UP

I have an laptop (inspiron 8100) and it has been behaving real weird the last few months.  It was sluggish and seemed bogged down.  Now it is completely acting up.  I tried reformatting the hard drive and reinstalling XP but the computer locks up.  Sometimes it will reinstall and other times it just locks up.  Even when it successfully reinstalls the OS it is only a matter of days before it completely locks up.  It also has a problem recognizing CD-Roms.  I will put one in and it will say there is none in there.  Then I will put a new one in and it will recognize than one and then recognize the other one.  I am at my wits end.  Should I try wiping out the entire hard drive instead of just reformatting?  Is it even the hard drive