Desktop grey screen after login and spinning wheel

I have a Mac desktop "Maverick''. On start I can login with a password but then I get a grey screen with a spinning wheel and nothing happen. I have tried to start up in safe mode, tried to reload Maverick, it started to reload, then stopped have way with the message Mac reload cannot be completed. Then I tried something else, hold key D on start to get a diagnostic, diagnostic result is ADP000, which means no problem found. But still cannot pass the grey screen and spinning wheel. Can anybody help?