I recently purchased a 20" iMac from the UK Apple refurb store, due to having been so busy at work and needing to have a good clear out before installing the new iMac it had remained in its box until early this afternoon. So I unboxed the unit, removed the stock 1GB RAM and replaced it with 4GB RAM from OWC, connected it and fired it up for the first time. All seemed to be going well until I noticed a flicker on the screen; it seemed to happen every now and then and I can only describe it as an intermittent flicker which at times appeared to be a grey flash. I continued using the system for a while until the display flickered again but instead of returning to its normal state it froze with a grey hue and became pixelated [note it was not the system that froze, it was still functioning], though it then returned to normal after several minutes. I contacted Apple Technical Support who had me do a number of things including removing 1 of the 2GB sticks and downloading and installing the iMac Graphics Firmware Update 1.0, the guy at Apple [who was really helpful BTW] then said to just wait and see if the fault re-occurred, and unfortunately it did. I contacted Technical Support a second time and they have now told me to take it to my local Apple Authorized Service Provider who fortunately are local to me. Is this normal? I was expecting them to tell me to send the unit in for repair. Has anyone else suffered a similar problem? The fact that it is an intermittent fault is what concerns me the most, what if the fault doesn't present itself whilst at the Service Provider?