Won't start up... Help

[Killar15]

My iMac wont strt up help me. it keeps telling me to restrt. i tried using the the safe boot but to no avail.. help me!

 

[MisterKeeks]

We are going to need 10x the info you provided- what model is it, did it exhibit any issues before this, how long does it go before it gives you the message, are there any lines of text running down the screen?