Hi! So I have a 24-inch iMac 2.8GHz. I've had long term issues that have persisted after three Apple Store repairs. I'm now running on an extended warranty because I reported the issues before my warranty actually expired. Anyway, the issues are as follows. - Really bad (and getting worse) screen ghosting - A lot of lagging/freezing/crashes - Sometimes the screen suddenly goes blank white or stripes and I have to force-restart So Apple have replaced the HD, the motherboard, the screen and the fan. I'm in the middle of a university degree and I can't really be without my computer so what should I do? Apple says they'll try to fix it again but should I demand a replacement? Thoughts? Thanks in advance!