I have problems with iMac alu 24" 2.4Ghz, 4 Gb RAM. First one I got had strange noises comming from its HD so I returned it and got a new one. This one worked great until yesterday when it started hanging constantly. As soon as Finder would load it would show beachball and stopped responding. Mouse still works but dock freezes and there's nothing to do but power off. I tried everything: cleaning caches, boot with cmd+alt+P+R, booting from Leopard CD disk utility says its ok, then I tried Tech Tools Pro all tests (surface scan ran for 4 hours) but not a single error. Btw, everything works in safe mode. Apple hardware test - all passed. I took USB external disk and installed OSX there and booted that system and than my iMac HD wouldn't show on Desktop at all!!! After a reboot it did but I couldn't acess any of the files, just got spinning wheel. Rebooted in safe mode again - everything ok. Called apple store that sold me iMac - the guy said to erease everything with 7 passes. Did that, left it overnight. In the morning while building GUID Partition map got error: Disk erease failed, input/output error. Does anyone have any advice? Is it hard disk or is it just the bug witd Disk utility I read about on the forums? What should I do? I used Mac for Pro applications and CS with few small apps like Perian, VLC, App zapper etc - no strange experiments and stuff. What to do?! Thanks!