So this has been an issue since Mavericks. Overall, everything works fine. But if I log into Yahoo Mail via any web browser, it will work fine at first and they the system will start locking up. I can move the cursor, but clicking on things will either give me a beachball or nothing will happen. I can walk away and let it sit for several minutes and nothing changes. Cursor still moves but clicks and keyboard commands are useless. Can't force quit or anything. Only solution is to do a forced reboot with the power button. I'm trying to figure out what to do to diagnose the issue. The problem has persisted through Yosemite and now El Capitan. When I ran the El Capitan beta on a partition, I didn't have the issue so it's something about my account or some program I use. But I don't know how to read crash logs or which logs to look at. I'd like to avoid a full, clean reinstall if I can. Any help would be appreciated.