What is wrong with this thing

Hello,

 

Inspiron 8500, 2.4ghz 512 Ram, 40gb hdd.  My system started acting very sluggish a month ago.  It takes 10-15 seconds to open a single window.  Also when I play video clips the audio streams but it only shows one frame of the movie every now and then.  My CPU is tacked out at 100% because it takes so long to grind and open the window or program.. afterwords it goes down to 10%.  I have not updated or installed anything recently to cause the situation that I can see.

 

I finally backed up all my data and decided to format and reload.   With just windows xp on and drivers loaded the system is acting exactly the same without any software.  After a fresh reload all the same symptoms listed above.  The system is acting like it is running at 120mhz. 

 

I'm at a loss of where to diagnose the problem.  My gut feeling is something hardware is going on.  I noticed recently my fan stopped operating on my laptop..  but I don't think that could be the cause.

 

If anyone has any feedback i'd appreciate it.

 

Thanks.