Finder blinking and I can't open it

Hello,

I have a problem since yesterday with my Macbook Pro (OS X Mavericks) : the finder (the menu bar, and the little line under the logo in the dock) keeps blinking. No possibility to open the finder, and it's the same with the applications, Disk utility, etc.

BUT I just tried to start the mac in "Safe mod" (Maj) and the finder is working normally !

So, how can I find where the problem is and eliminate it ?

Thank you !