when i start up my imac, thers is a loading bar and spinning circle. the loading bar goes to about 25% done then shut off again.
i need help getting out of the start up screen and into my desktop.
iMac
Welcome to Apple Support Communities
First have a look at > Mac OS X: Gray screen appears during startup
However, if it is shutting off during startup as your title indicates, then run the Extended Hardware Test as per > Using Apple Hardware Test