I have been having problems with my iMac; it slow downs to a halt and it hangs, the ball keeps rolling, and my screen becomes distorted, with lines in the middle, and also, the screen stops refreshing. i.e. Portions of prior pages stays on the screen. Any idea what the reason may be?
The system will not allow you to repair the disk from which it is booted. The suggested way around this is to boot from the install media and then run Disk Utility from there.
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Slow and hanging
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