Issue: Desktop flashes and Finder can't open

[dhokes]

I restarted my iMac running Yosemite, however now when I turn it on, the desktop flashes repeatedly and it appears as though Finder can't open. I can't seem to do anything. :s

Any ideas why this is the case and how to resolve this issue?

I've just reset the system and trying to run in safe mode. I'm still on the apple logo screen and the bar is moving up very slowly. I've managed to log in, in safe mode.