Hello All,
I’m looking for some advice. We have an iMac 27 inch (late 2013) with processor 3.2. GHz Quad-Core Intel Core i5, Memory 8GB 1600 MHz DDR3, Graphics NVIDIA GeForce GT 755M 1 GB. We were running OS X 10.10: Yosemite on it for years with no problems. In the last few tears it started...