I didn't even ungrade knowingly, its just that I was getting constant messages asking me if I wanted to update my apps and I just clicked update everything.
Yessss... that was rather sneaky. OS upgrades ought to be shown as such, and not simply put in the software upgrades box.
In fact, it's usually other progs that cause issues when you upgrade, as some software producers take short cuts, which then fall foul of changes to the OS. There's also quite a lot you can do to keep things running smoothly and quickly. One thing that's worth knowing is that the more items you have on the desktop, the slower your Mac will start. That's because the finder treats each desktop item as a separate window, so a lot of things left there can slow the thing down significantly.
In advance of Yosemite they've just pushed out a big security update. That's an important one, but once it's installed it's a good idea to restart your computer.
