Mackeeper may be too good to be true!
A friend's computer is too slow to play videos without pauses.  He mentioned he has "Mackeeper".  I googled "mackeeper problems", found a dire warning from the apple community that called the program "malware".  Don't use Mac myself, but if you want that program or any similar program, I'd suggest googling and researching first.

I don't know how or why he got mackeeper, but beware of those "free" offers to scan your computer for problems.  They'll find many "imaginary" problems, then offer to download a program for a small fee to "fix" them. Or they'll offer to speed up your computer.  They're selling snake oil.  (They throw in the malware for free.) 

Gmail Attack Warning
I received a warning from google that the Chinese and Taiwanese attempted to hack my gmail account, and that I should immediately change my password. And I did. I think the email was legitimate, but I immediately changed my password again from my gmail page.

If you get a similar warning (from any service you use), I suggest you follow the steps below. They are MUCH SAFER!

Close the warning windows.
Log on directly to the the website for the warning you got. (gmail)).
Use the account management features there to change your password. It's not imossible that the warning is bogus, and that the "fake" page with the warning will record your password when you "change" it.