My iMac sometimes became unresponsive. Also, the key chain was always popping up to ask for my password. They looked at computer and discovered that I had a hard drive problem. They replaced my hard drive with a solid state drive. They fixed my key chain issue. Now my iMac works GREAT. With the new hard drive, I am certain I will get many more years out of my iMac as it runs super fast now. Thanks for all your help.