Since upgrading from Snow Leopard to Yosemite, about five days ago... Random, intermittent, sporadic, and periodic: Hangs, Beachballs, Beachball, SBOD. . . . MBP MacBook Pro 64-Bit Core2Duo 2.53GHz MacBookPro5,4 Mid-2009 15" MC118LL/A Unibody aluminum. Upgraded RAM, Internal HDD, and new battery in 2013. Currently 8GB RAM, 1TB HD, Mac OS X 10.10.1 Yosemite . . . External Buffalo 2TB for TimeMachine backups Yosemite is awesome, especially since I have an iPad Air, as well as a MacBook Pro mid-2009. However, there are some PROBLEMS Yes, I know I SHOULDDA wouldda couldda done a CLEAN INSTALL... . . . but I shudder to think of all the things that I would have to remember to setup... Now, I have the dreaded SBOD, aka Spinning BEACHBALL of Death, and frequent inexplicable hangs. No CPU or DISC or RAM or NETWORK bottlenecks, according to Activity Monitor, at least. Something in the system just HANGS for 30~60 seconds (or more) every 15~20 minutes (or less.) Sometimes it just freezes/hangs (with or without the SBOD.) Sometimes the mouse still moves and the clock still shows ticking time but the DOCK will not expand or come alive, and clicks do not seem to register in the event queue. SOMETIMES the system comes back alive after 30~60 seconds, sometimes after a few minutes sometimes not at all waited overnight, spinning beachball still there in the morning... Bummer!!! ANNOYING!!!!! Any suggestions, please? How to diagnose the cause of these Yosemite hangs/beachballs/SBODs? HELP?!