Wont start

I have yosemite 10.10.2

I tried to update to the .17 version.
But it get stuck on the update everytime.
So i downloaded the newest version and installed it manual.
I went thinking allot with the rainbow ball…
Computer restart, deinstalling and installing wont work.
Installing older versions also does not work anymore.

When i wait 5 to 10 minutes sometimes it works and sometimes not.

Any idea what this could be?