vernon128,
One of your memory modules has gone bad.
You can remove one at a time until you find the one that is bad.
Here is a link to your service manual that will walk you through the steps to remove the memory.
Starts on page 69.
If you don't feel comfortable doing it yourself, here is a link to a number that you can call HP and see what repair options they may have.
Your system should still be covered under you factory warranty.
Let me know how everything goes.