Today iTunes kept freezing and I got the spinning beachball, and after a while I could get it to close using force quit. This happened several times so I thought I'd restart the computer, however the computer wouldn't restart and I got an error window saying that the Mac OS installation couldn't be completed and it brought up an installation log which it said that I could save. I tried to save the installation log but it wouldn't allow me, and after four or five attempts at a restart it finally booted up. I immediately tried to backup via time machine, which then also crashed and I had to force close the Mac as everything became unresponsive. Fortunately it started back up without any more issues and is now letting me run a back up. Does anyone have any idea why this happened, what caused it, whether there's a fix or whether it's a sign of a terminal issue? I have run first aid on disk utility and it's not finding any faults. The only updates that have been completed recently are safari update and cleanmydrive2, both of which updated 4 days ago. Any help would be greatly appreciated.