Apple/MacBook Pro Professionals out there????? (Beijing)

I have a macBook Pro and I'm having two major problems that I wonder if anyone can help me with. One is that the computer regularly gives me the "circle of death" (the little rainbow wheel that spins around and around, endlessly). I can only get out of the loop if I shut down the computer and start again. That doesn't sound like a way to run a computer. I have MacKeeper and 12.8 GB of "duplicate files", but when I deleted a "duplicate", both files were gone. :-( So I stopped doing that after three times).
And my second problem is that when I have to restart the computer, I get the pop up window that states that there is a problem with my start up and I need to delete files to make room, or something like that. You Pros know the pop up I'm talking about. :-)
Can anyone out there in cyber land help me with SIMPLE instructions to walk me through this to make my mac run smoother, because right now I am very frustrated, plus the speed of the operation system is so slow, but that may just be China. :-( If you can offer a phone number for assistance too and I can Skype you to fix this, that would be great.
Thanks in advance. I love this Forum.
Cheers,
Marty